kernel-yocto: don't apply config metadata patches twice

(From OE-Core rev: 0b88ed0af350c609ce8075e7d89ca7db91486858)

Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes/kernel-yocto.bbclass

@@ -36,7 +36,10 @@ def find_patches(d,subdir):
             if subdir == patchdir:
                 patch_list.append(local)
         else:
-            patch_list.append(local)
+            # skip the patch if a patchdir was supplied, it won't be handled
+            # properly
+            if not patchdir:
+                patch_list.append(local)
 
     return patch_list