uvision5 - get_toolchain method

same solution as in PR #1687 but for Keil v5

Author: ohagendorf

workspace_tools/export/uvision5.py

@@ -44,6 +44,8 @@ class Uvision5(Exporter):
             # target is not supported yet
             continue
 
+    def get_toolchain(self):
+        return TARGET_MAP[self.target].default_toolchain
 
     def generate(self):
         """ Generates the project files """