Build: Move Storage asset defs to build variables

Removes the MAX_ASSET_SIZE and NUM_ASSETS storage definitions from
flash_layout.h and adds replacement build variables for them. This
allows for greater customisation at build time and reduces duplication
between platforms.

Change-Id: If5d20ee0cb8dede28513c10572da594c02b4ee89
Signed-off-by: Jamie Fox <jamie.fox@arm.com>
diff --git a/config/config_default.cmake b/config/config_default.cmake
index 340eff5..5c2f189 100644
--- a/config/config_default.cmake
+++ b/config/config_default.cmake
@@ -71,17 +71,21 @@
 ############################ Partitions ########################################
 
 set(TFM_PARTITION_PROTECTED_STORAGE     ON          CACHE BOOL      "Enable Protected Storage partition")
-set(PS_CREATE_FLASH_LAYOUT              ON          CACHE BOOL      "Create flash fs if it doesn't exist for Protected Storage partition")
+set(PS_CREATE_FLASH_LAYOUT              ON          CACHE BOOL      "Create flash FS if it doesn't exist for Protected Storage partition")
 set(PS_ENCRYPTION                       ON          CACHE BOOL      "Enable encryption for Protected Storage partition")
 set(PS_RAM_FS                           OFF         CACHE BOOL      "Enable emulated RAM FS for platforms that don't have flash for Protected Storage partition")
 set(PS_ROLLBACK_PROTECTION              ON          CACHE BOOL      "Enable rollback protection for Protected Storage partition")
 set(PS_VALIDATE_METADATA_FROM_FLASH     ON          CACHE BOOL      "Validate filesystem metadata every time it is read from flash")
-set(PS_CRYPTO_AEAD_ALG                  PSA_ALG_GCM CACHE STRING    "The AEAD algorithm to use for authenticated encryption in protected storage")
+set(PS_MAX_ASSET_SIZE                   "2048"      CACHE STRING    "The maximum asset size to be stored in the Protected Storage area")
+set(PS_NUM_ASSETS                       "10"        CACHE STRING    "The maximum number of assets to be stored in the Protected Storage area")
+set(PS_CRYPTO_AEAD_ALG                  PSA_ALG_GCM CACHE STRING    "The AEAD algorithm to use for authenticated encryption in Protected Storage")
 
 set(TFM_PARTITION_INTERNAL_TRUSTED_STORAGE ON       CACHE BOOL      "Enable Internal Trusted Storage partition")
-set(ITS_CREATE_FLASH_LAYOUT             ON          CACHE BOOL      "Create flash fs if it doesn't exist for Interal Trusted Storage partition")
-set(ITS_RAM_FS                          OFF         CACHE BOOL      "Enable emulated RAM FS for platforms that don't have flash for Interal Trusted Storage partition")
+set(ITS_CREATE_FLASH_LAYOUT             ON          CACHE BOOL      "Create flash FS if it doesn't exist for Internal Trusted Storage partition")
+set(ITS_RAM_FS                          OFF         CACHE BOOL      "Enable emulated RAM FS for platforms that don't have flash for Internal Trusted Storage partition")
 set(ITS_VALIDATE_METADATA_FROM_FLASH    ON          CACHE BOOL      "Validate filesystem metadata every time it is read from flash")
+set(ITS_MAX_ASSET_SIZE                  "512"       CACHE STRING    "The maximum asset size to be stored in the Internal Trusted Storage area")
+set(ITS_NUM_ASSETS                      "10"        CACHE STRING    "The maximum number of assets to be stored in the Internal Trusted Storage area")
 set(ITS_BUF_SIZE                        ""          CACHE STRING    "Size of the ITS internal data transfer buffer (defaults to ITS_MAX_ASSET_SIZE if not set)")
 
 set(TFM_PARTITION_CRYPTO                ON          CACHE BOOL      "Enable Crypto partition")