Build: Fix arch type of Cortex-M0plus in GNUARM

The arch type of Cortex-M0plus should be "armv6s-m" instead of
"armv6-m" in GNU Arm embedded toolchain. Otherwise, compiling will
fail because "armv6-m" type doesn't support SVC.
Fix the arch type values in GNUARM cmake files.
Add an arch type string "ARMv6S-M" for Cortex-M0plus in GNUARM.
Because Armclang doesn't have a dedicated flag as "armv6s-m", two
strings "ARMv6-M" and "ARMv6S-M" exist and stand for Cortex-M0plus
arch type in Armclang and GNUARM respectively.

Change-Id: I59e9b9837012fb8dbbae59beacfd6cb293548747
Signed-off-by: David Hu <david.hu@arm.com>
diff --git a/BuildMbedCrypto.cmake b/BuildMbedCrypto.cmake
index 3f573c9..fb51c98 100644
--- a/BuildMbedCrypto.cmake
+++ b/BuildMbedCrypto.cmake
@@ -1,5 +1,5 @@
 #-------------------------------------------------------------------------------
-# Copyright (c) 2017-2019, Arm Limited. All rights reserved.
+# Copyright (c) 2017-2020, Arm Limited. All rights reserved.
 #
 # SPDX-License-Identifier: BSD-3-Clause
 #
@@ -61,7 +61,8 @@
 
 # Workaround Mbed TLS issue https://github.com/ARMmbed/mbedtls/issues/1077
 if ((${ARM_CPU_ARCHITECTURE} STREQUAL "ARMv8-M.BASE") OR
-   (${ARM_CPU_ARCHITECTURE} STREQUAL "ARMv6-M"))
+    (${ARM_CPU_ARCHITECTURE} STREQUAL "ARMv6-M") OR
+    (${ARM_CPU_ARCHITECTURE} STREQUAL "ARMv6S-M"))
    string(APPEND MBEDCRYPTO_C_FLAGS " -DMULADDC_CANNOT_USE_R7")
 endif()