UefiCpuPkg/PiSmmCpuDxeSmm: Clean up CheckFeatureSupported()

UefiCpuPkg/PiSmmCpuDxeSmm: Clean up CheckFeatureSupported()

Removed EFIAPI and parameter from CheckFeatureSupported() and removed
CheckProcessorFeature() totally.

Cc: Michael Kinney <michael.d.kinney@intel.com>
Cc: Feng Tian <feng.tian@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Jeff Fan <jeff.fan@intel.com>
Reviewed-by: Feng Tian <feng.tian@intel.com>
Reviewed-by: Michael Kinney <michael.d.kinney@intel.com>
Regression-tested-by: Laszlo Ersek <lersek@redhat.com>