Add MWAIT Cx support for Zhaoxin CPUs

zhaoxin inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I8WZ4L


CVE: NA

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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.

Signed-off-by: leoliu-oc <leoliu-oc@zhaoxin.com>