x86: Implement TSC adjust feature for HVM guest

x86: Implement TSC adjust feature for HVM guest

IA32_TSC_ADJUST MSR is maintained separately for each logical
processor. A logical processor maintains and uses the IA32_TSC_ADJUST
MSR as follows:
1). On RESET, the value of the IA32_TSC_ADJUST MSR is 0;
2). If an execution of WRMSR to the IA32_TIME_STAMP_COUNTER MSR adds
    (or subtracts) value X from the TSC, the logical processor also
    adds (or subtracts) value X from the IA32_TSC_ADJUST MSR;
3). If an execution of WRMSR to the IA32_TSC_ADJUST MSR adds (or
    subtracts) value X from that MSR, the logical processor also adds
    (or subtracts) value X from the TSC.

This patch provides tsc adjust support for hvm guest, with it guest OS
would be happy when sync tsc.

Signed-off-by: Liu, Jinsong <jinsong.liu@intel.com>
Committed-by: Jan Beulich <jbeulich@suse.com>