Core: Remove legacy veneer support

Details:
 - TFM_PARTITION_SPECIFIC_ERROR_MIN is removed as the range limitation
   of the secure service error codes are not present
 - unify the veneer section sizes in region_defs.h across the
   platforms. Also remove related FIXMEs
 - remove non-uniform veneer related code from TF-M Core

Change-Id: I23961f36810ab768955b8a3ecaf63b3945d329f7
Signed-off-by: Mate Toth-Pal <mate.toth-pal@arm.com>
diff --git a/interface/include/tfm_platform_api.h b/interface/include/tfm_platform_api.h
index 9c4e023..fbbd757 100644
--- a/interface/include/tfm_platform_api.h
+++ b/interface/include/tfm_platform_api.h
@@ -23,12 +23,6 @@
 #define TFM_PLATFORM_API_VERSION_MAJOR (0)
 #define TFM_PLATFORM_API_VERSION_MINOR (3)
 
-/* The return value is shared with the TF-M partition status value.
- * The Platform return codes shouldn't overlap with predefined TFM status
- * values.
- */
-#define TFM_PLATFORM_ERR_OFFSET (TFM_PARTITION_SPECIFIC_ERROR_MIN)
-
 /*!
  * \enum tfm_platform_err_t
  *
@@ -37,7 +31,7 @@
  */
 enum tfm_platform_err_t {
     TFM_PLATFORM_ERR_SUCCESS = 0,
-    TFM_PLATFORM_ERR_SYSTEM_ERROR = TFM_PLATFORM_ERR_OFFSET,
+    TFM_PLATFORM_ERR_SYSTEM_ERROR,
     TFM_PLATFORM_ERR_INVALID_PARAM,
     TFM_PLATFORM_ERR_NOT_SUPPORTED,