include: sys: Simplify sys_mutex_unlock
include: sys: Simplify sys_mutex_unlock

Remove redundant if() statements that are already included with
k_mutex_unlock()

Relates to issue #32994

Signed-off-by: Guðni Már Gilbert <a67b89b8b42b5e36ccc84f3061af0045ff2a5bff@gmail.com>

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