KVM: x86: Expose fast short REP MOV for supported cpuid

For CPU supporting fast short REP MOV (XF86_FEATURE_FSRM) e.g Icelake,
Tigerlake, expose it in KVM supported cpuid as well.

Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Message-Id: <20200323092236.3703-1-zhenyuw@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>