SecurityPkg: Use PcdGetSize to get the size of VOID* PCD value.

SecurityPkg: Use PcdGetSize to get the size of VOID* PCD value.

PcdLib introduces generic API to get the size of VOID* PCD value.
Update Pei and Dxe RsaGuidedLib to use generic PCD API instead of GetEx API.
This change can remove PCD type limitation in these two libraries.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Liming Gao <liming.gao@intel.com>
Reviewed-by: Star Zeng <star.zeng@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18277 6f19259b-4bc3-4df7-8a09-765794883524