fw/msr_feature_control: add support to set MSR_IA32_FEATURE_CONTROL

fw/msr_feature_control: add support to set MSR_IA32_FEATURE_CONTROL

OS usually expects BIOS to set certain bits in MSR_IA32_FEATURE_CONTROL
for some features (e.g. VMX and LMCE). QEMU provides a fw_cfg file
"etc/msr_feature_control" to advise bits that should be set in
MSR_IA32_FEATURE_CONTROL. If this file exists, SeaBIOS will set the
advised bits in that MSR.

Signed-off-by: Haozhong Zhang <haozhong.zhang@intel.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 20160622065324.23812-1-haozhong.zhang@intel.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
(cherry picked from commit 20f83d5c7c0f9ae5f775b6701c205349abe003fb)