SST: Add capability to use RAM instead of flash

The execution of SST regression tests reduces the life of the flash
memory as they write/erase multiple times in the memory.
This patch adds the capability to use RAM instead of flash memory
to run SST regression tests.

Change-Id: Ie6eff8e8deebe9f8d58dd13abc5e4a4148cd6994
Signed-off-by: Marc Moreno <marc.morenoberengue@arm.com>
diff --git a/CommonConfig.cmake b/CommonConfig.cmake
index 77ba88e..3ed12bd 100644
--- a/CommonConfig.cmake
+++ b/CommonConfig.cmake
@@ -208,6 +208,14 @@
 	if (NOT DEFINED SST_ENABLE_PARTIAL_ASSET_RW)
 		set (SST_ENABLE_PARTIAL_ASSET_RW ON)
 	endif()
+
+	if (NOT DEFINED SST_RAM_FS)
+		if (REGRESSION)
+			set (SST_RAM_FS ON)
+		else()
+			set (SST_RAM_FS OFF)
+		endif()
+	endif()
 endif()
 
 if (NOT DEFINED MBEDTLS_DEBUG)