Updating default args and docs

- Updated the document with latest supported toolchain information
- Defaulted CPU_ARCH to armv8m_ml if not passed from CMake arguments.

Signed-off-by: Gowtham Siddarth <gowtham.siddarth@arm.com>
diff --git a/api-tests/CMakeLists.txt b/api-tests/CMakeLists.txt
index fa949a3..d1bc028 100644
--- a/api-tests/CMakeLists.txt
+++ b/api-tests/CMakeLists.txt
@@ -96,8 +96,6 @@
 _check_arguments("SUITE")
 # Check for PSA_INCLUDE_PATHS command line argument
 _check_arguments("PSA_INCLUDE_PATHS")
-# Check for CPU_ARCH command line argument
-_check_arguments("CPU_ARCH")
 
 string(TOLOWER ${SUITE} SUITE_LOWER)
 
@@ -191,12 +189,17 @@
         message(STATUS "[PSA] : Defaulting compiler to ${TOOLCHAIN}")
 endif()
 
-# Check for CPU architecture
-if(NOT ${CPU_ARCH} IN_LIST PSA_CPU_ARCH_SUPPORT)
-	message(FATAL_ERROR "[PSA] : Error: Unsupported value for -DCPU_ARCH=, supported CPU arch are : ${PSA_CPU_ARCH_SUPPORT}")
+if(${TOOLCHAIN} STREQUAL "ARMCLANG" OR ${TOOLCHAIN} STREQUAL "GNUARM")
+    if(NOT DEFINED CPU_ARCH)
+	    message(FATAL_ERROR "[PSA] : Error: -DCPU_ARCH option missing")
+    else()
+        # Check for CPU architecture
+        if(NOT ${CPU_ARCH} IN_LIST PSA_CPU_ARCH_SUPPORT)
+	        message(FATAL_ERROR "[PSA] : Error: Unsupported value for -DCPU_ARCH=, supported CPU arch are : ${PSA_CPU_ARCH_SUPPORT}")
+        endif()
+    endif()
 endif()
 
-
 # Check for VERBOSE
 if(NOT DEFINED VERBOSE)
 	set(VERBOSE 3 CACHE INTERNAL "Default VERBOSE value" FORCE)
diff --git a/api-tests/docs/sw_requirements.md b/api-tests/docs/sw_requirements.md
index 0a22145..e0424f3 100644
--- a/api-tests/docs/sw_requirements.md
+++ b/api-tests/docs/sw_requirements.md
@@ -5,7 +5,7 @@
 
 - Host Operating System     : Ubuntu 16.04, Windows 10
 - Scripting tools           : Python 3.1.7
-- Compiler toolchain        : GNU Arm Embedded Toolchain 6.3.1, Arm Compiler v6.7
+- Compiler toolchain        : GNU Arm Embedded Toolchain 6.3.1, Arm Compiler v6.7, GCC 5.4.0 32-Bit (Linux Host), MinGW 6.3.0 32-Bit (Windows Host)
 - Build tools               : CMake 3.10
 
 **Note**: To compile the test suite code, at least one of the above supported compiler toolchains