!3177 [OLK-6.6] Add MWAIT Cx support for Zhaoxin CPUs

Merge Pull Request from: @leoliu-oc 
 
When the processor is idle，low-power idle states (C-states) can be used to save power. For Zhaoxin processors，there are two methods to enter idle states. One is HLT instruction and legacy method of I/O reads from the
ACPI-defined register (known as P_LVLx)，the other one is MWAIT instruction with idle states hints.

Default for legacy operating system，HLT and P_LVLx I/O reads are used for Zhaoxin Processors to enter idle states, but we have checked on some Zhaoxin platform that MWAIT instruction is more efficient than P_LVLx I/O
reads and HLT, so we add MWAIT Cx support for Zhaoxin Processors.

### Issue
https://gitee.com/openeuler/kernel/issues/I8WZ4L

### Test
Pass: can use the MWAIT instruction to enter low-power idle states 
 
Link:https://gitee.com/openeuler/kernel/pulls/3177

 

Reviewed-by: Jason Zeng <jason.zeng@intel.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>