testsuite: generalize timestamp_serialize for all ARC CPUs
testsuite: generalize timestamp_serialize for all ARC CPUs

Generalize timestamp_serialize defenition for all ARC CPUs
instead of ARCv2 only.

Signed-off-by: Eugeniy Paltsev <ec089b543c2604b626d7ce60c03e4d074ed102c7@synopsys.com>

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