UefiCpuPkg/Include: Add VMX MSR register structures

UefiCpuPkg/Include: Add VMX MSR register structures

https://bugzilla.tianocore.org/show_bug.cgi?id=279

Add MSR_IA32_VMX_BASIC_REGISTER and IA32_VMX_MISC_REGISTER
structures with the bit fields for these two MSRs.   Also
add MSEG_HEADER structure whose base address is in the
MsegBase field of MSR_IA32_SMM_MONITOR_CTL_REGISTER.

Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Jeff Fan <jeff.fan@intel.com>
Cc: Feng Tian <feng.tian@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Michael Kinney <michael.d.kinney@intel.com>
Reviewed-by: Jeff Fan <jeff.fan@intel.com>