Initialize the XSS exit bitmap.  It is zero so there should be no XSAVES
or XRSTORS exits.
Signed-off-by: NWanpeng Li <wanpeng.li@linux.intel.com>
Reviewed-by: NRadim Krčmář <rkrcmar@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>