xtensa: change CONFIG_ATOMIC_OPERATIONS_ARCH to imply
xtensa: change CONFIG_ATOMIC_OPERATIONS_ARCH to imply

Xtensa cores are highly configurable so each SoC may not have
the needed instructions for the hardware assisted atomic
operations. So instead of selecting the arch-specific atomic
operations kconfig, do a "imply" instead. So SoC or board
configs can disable this.

Signed-off-by: Daniel Leung <d94e04d205b5962d7873a139ef298b03c1717f72@intel.com>

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