checkpatch: Add UTIL_CAT support to checkpatch
checkpatch: Add UTIL_CAT support to checkpatch

Checkpatch was checking for macro concats (##), however
we often use UTIL_CAT to allow for multiple macro expansion passes
to succeed.

Signed-off-by: Tom Burdick <63c280986e32082c9e27a1a69ac8b19e3d0c6b4b@intel.com>

zephyrproject-rtos/zephyr,galak/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,galak/zephyr,finikorg/zephyr,finikorg/zephyr,finikorg/zephyr,galak/zephyr,galak/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr