SST: Crypto service binding

Refactors the SST crypto interface to call into the Crypto service
instead of Mbed TLS. Removes the Mbed TLS build from the SST build
files.

Change-Id: Iff3bdf799c66127c7b71a9f5a8c54e887134a8e8
Signed-off-by: Jamie Fox <jamie.fox@arm.com>
diff --git a/CommonConfig.cmake b/CommonConfig.cmake
index eb07016..8f24174 100644
--- a/CommonConfig.cmake
+++ b/CommonConfig.cmake
@@ -229,7 +229,7 @@
 	endif()
 endif()
 
-##Set mbedTLS compiler flags and variables for secure storage, audit log and crypto
+##Set Mbed TLS compiler flags and variables for audit log and crypto
 set(MBEDTLS_C_FLAGS_SERVICES "-D__ARM_FEATURE_CMSE=3 -D__thumb2__ ${COMMON_COMPILE_FLAGS_STR} -I${CMAKE_CURRENT_LIST_DIR}/platform/ext/common")
 
 #Default TF-M secure storage flags.