x86: use LFENCE instead of CPUID before reading TSC for x86_64
x86: use LFENCE instead of CPUID before reading TSC for x86_64

According to Intel 64 and IA-32 Architectures Software
Developer’s Manual, volume 3, chapter 8.2.5, LFENCE provides
a more efficient method of controlling memory ordering than
the CPUID instruction. So use LFENCE here, as all 64-bit
CPUs have LFENCE.

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

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