SecurityPkg: Clean up unused files in RngDxe

SecurityPkg: Clean up unused files in RngDxe

Clean up files in RngDxe/IA32 and RngDxe/X64 that are subsumed
by files in BaseRngLib.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Thomas Palmer <thomas.palmer@hpe.com>
Reviewed-by: Samer El-Haj-Mahmoud <elhaj@hpe.com>
Reviewed-by: Michael Kinney <michael.d.kinney@intel.com>
Reviewed-by: Chao Zhang <chao.b.zhang@intel.com>
Reviewed-by: Qin Long <qin.long@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18592 6f19259b-4bc3-4df7-8a09-765794883524