!272 [openEuler-1.0-LTS] 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 CPI-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/I62TOM

### Test
N/A

### Known Issue
N/A

### Default config change
N/A

 
 
Link:https://gitee.com/openeuler/kernel/pulls/272

 
Reviewed-by: Laibin Qiu <qiulaibin@huawei.com>
Signed-off-by: Xie XiuQi <xiexiuqi@huawei.com>