workspace_tools/toolchains/gcc.py: Use 'cortex-m0plus' support for Cortex M0+

This support is supported by:
- gcc-arm-none-eabi-4_7-2013q1
- gcc-arm-none-eabi-4_9-2014q4

Author: oliviermartin

workspace_tools/toolchains/gcc.py

@@ -34,7 +34,7 @@ def __init__(self, target, options=None, notify=None, macros=None, silent=False,
         mbedToolchain.__init__(self, target, options, notify, macros, silent)
 
         if target.core == "Cortex-M0+":
-            cpu = "cortex-m0"
+            cpu = "cortex-m0plus"
         elif target.core == "Cortex-M4F":
             cpu = "cortex-m4"
         else: