builder:siwisdk: Fix build warning with cpp files

CFLAG defined in Common c/c++ build flags causing build warning

Signed-off-by: Ajay Bhargav <[email protected]>

Author: ajaybhargav

builder/framework/siwisdk.py

@@ -115,6 +115,9 @@ def gen_fota_file(target, source, env):
         "-Wall",
         "-mthumb",
         "-mthumb-interwork",
+    ],
+
+    CFLAGS=[
         "-std=gnu11"
     ],