KVM: x86: Implement Intel PT MSRs read/write emulation

This patch implement Intel Processor Trace MSRs read/write
emulation.
Intel PT MSRs read/write need to be emulated when Intel PT
MSRs is intercepted in guest and during live migration.

Signed-off-by: Chao Peng <chao.p.peng@linux.intel.com>
Signed-off-by: Luwei Kang <luwei.kang@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>