Platform: Fix ITS_FLASH_PROGRAM_UNIT on Musca-B1

Flash writes must be aligned to 4-bytes on Musca-B1 with the emulated
flash driver.

Change-Id: Ica6e03d749e2eb5146605cc4f7fbea0c9e330c4c
Signed-off-by: Jamie Fox <jamie.fox@arm.com>
diff --git a/platform/ext/target/musca_b1/partition/flash_layout.h b/platform/ext/target/musca_b1/partition/flash_layout.h
index 283e15d..b6e83a1 100644
--- a/platform/ext/target/musca_b1/partition/flash_layout.h
+++ b/platform/ext/target/musca_b1/partition/flash_layout.h
@@ -195,7 +195,7 @@
 /* Number of ITS_SECTOR_SIZE per block */
 #define ITS_SECTORS_PER_BLOCK   (0x1)
 /* Specifies the smallest flash programmable unit in bytes */
-#define ITS_FLASH_PROGRAM_UNIT  (0x1)
+#define ITS_FLASH_PROGRAM_UNIT  (0x4)
 /* The maximum asset size to be stored in the ITS area */
 #define ITS_MAX_ASSET_SIZE      (512)
 /* The maximum number of assets to be stored in the ITS area */