MdeModulePkg: PiSmmCore: Remove confusing CopyMem() of SMM_ENTRY_CONTEXT

MdeModulePkg: PiSmmCore: Remove confusing CopyMem() of SMM_ENTRY_CONTEXT

A subset of fields in the EFI_SMM_SYSTEM_TABLE2 structure are identical
to the fields in the SMM_ENTRY_CONTEXT structure.  CopyMem() is used to
transfer the contents of the SMM_ENTRY_CONTEXT structure into the
EFI_SMM_SYSTEM_TABLE2.  This is confusing because SMM_ENTRY_CONTEXT is
not used in the declaration of EFI_SMM_SYSTEM_TABLE2 and field contents
are transferred without any reference to individual field names (e.g.
CurrentlyExecutingCpu).  In order to make the code easier to maintain
and understand, the CopyMem() is replaced with statements that transfer
each field of SMM_ENTRY_CONTEXT into EFI_SMM_SYSTEM_TABLE2.

Reported-by: Laszlo Ersek <lersek@redhat.com>
Link: http://article.gmane.org/gmane.comp.bios.edk2.devel/3567
Cc: Feng Tian <feng.tian@intel.com>
Cc: Jeff Fan <jeff.fan@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Michael Kinney <michael.d.kinney@intel.com>
Reviewed-by: Feng Tian <feng.tian@intel.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18716 6f19259b-4bc3-4df7-8a09-765794883524