Update Cortex-A build errors

Author: theotherjimmy

tools/build_api.py

@@ -443,7 +443,7 @@ def scan_resources(src_paths, toolchain, dependencies_paths=None,
             "rtos" in toolchain.config.lib_config_data):
         if "Cortex-A" in toolchain.target.core:
             raise NotSupportedException(
-                ("%s Will be supported in mbed OS 5.6. "
+                ("%s Will be supported in a future version of Mbed OS. "
                     "To use the %s, please checkout the mbed OS 5.4 release branch. "
                     "See https://developer.mbed.org/platforms/Renesas-GR-PEACH/#important-notice "
                     "for more information") % (toolchain.target.name, toolchain.target.name))

tools/options.py

@@ -122,7 +122,7 @@ def mcu_is_enabled(parser, mcu):
     if "Cortex-A" in TARGET_MAP[mcu].core:
         args_error(
             parser,
-            ("%s Will be supported in mbed OS 5.6. "
+            ("%s Will be supported in a future version of Mbed OS. "
              "To use the %s, please checkout the mbed OS 5.4 release branch. "
              "See https://developer.mbed.org/platforms/Renesas-GR-PEACH/#important-notice "
              "for more information") % (mcu, mcu))