util/lint: Don't check for Kconfig.name in common directory

`src/mainboard/*/common` doesn't need a Kconfig.name, so don't check
for one.

Change-Id: I6c69c174287f7f068e28ed9c33b9b5542c87ca60
Signed-off-by: Sean Rhodes <sean@starlabs.systems>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/89051
Reviewed-by: Matt DeVillier <matt.devillier@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Martin L Roth <gaumless@gmail.com>

util/lint/lint-stable-006-board-name

@@ -17,6 +17,10 @@ for i in src/mainboard/*/; do
 done
 
 for i in src/mainboard/*/*/; do
+  case "$i" in
+    */common/) continue ;;
+  esac
+
   if [ -r $i/Kconfig ]; then
     if [ ! -r $i/Kconfig.name ]; then
       BOARD="$(grep -A2 MAINBOARD_PART_NUMBER $i/Kconfig | tail -1 | cut -f2 -d\")"