checkpatch.pl: Make CONFIG_IS_ENABLED(CONFIG_*) an error

CONFIG_IS_ENABLED() takes the kconfig name without the CONFIG_ prefix,
e.g. CONFIG_IS_ENABLED(CLK) for CONFIG_CLK. Make including the prefix
an error in checkpatch.pl so calls in the wrong format aren't
accidentally reintroduced.

Signed-off-by: Alper Nebi Yasak <alpernebiyasak@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/patman/test_checkpatch.py b/tools/patman/test_checkpatch.py
index 792196e..f71c70f 100644
--- a/tools/patman/test_checkpatch.py
+++ b/tools/patman/test_checkpatch.py
@@ -405,6 +405,12 @@
         pm.add_line('include/myfile.h', '#include <dm.h>')
         self.checkSingleMessage(pm, 'BARRED_INCLUDE_IN_HDR', 'error')
 
+    def testConfigIsEnabledConfig(self):
+        """Test for accidental CONFIG_IS_ENABLED(CONFIG_*) calls"""
+        pm = PatchMaker()
+        pm.add_line('common/main.c', 'if (CONFIG_IS_ENABLED(CONFIG_CLK))')
+        self.checkSingleMessage(pm, 'CONFIG_IS_ENABLED_CONFIG', 'error')
+
 
 if __name__ == "__main__":
     unittest.main()