CI: Exclude MbedTLS subtree for CONFIG checks

Since MbedTLS is an external repo with its own coding style,
exclude it from Azure and gitlab CI CONFIG checks.

Signed-off-by: Raymond Mao <raymond.mao@linaro.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 7d62103..2a52e15 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -159,7 +159,8 @@
     # have no matches.
     - git grep -E '^#[[:blank:]]*(define|undef)[[:blank:]]*CONFIG_'
         :^doc/ :^arch/arm/dts/ :^scripts/kconfig/lkc.h
-        :^include/linux/kconfig.h :^tools/ :^dts/upstream/ &&
+        :^include/linux/kconfig.h :^tools/ :^dts/upstream/
+        :^lib/mbedtls/external :^lib/mbedtls/mbedtls_def_config.h &&
         exit 1 || exit 0
 
 # build documentation