MdeModulePkg PeiCore: Not assume PpiDescriptor and Ppi in same range

MdeModulePkg PeiCore: Not assume PpiDescriptor and Ppi in same range

Current code assumes PpiDescriptor and Ppi are in same range
(heap/stack/hole).

This patch removes the assumption.

Descriptor needs to be converted first. It is also handled by this patch.

Cc: Liming Gao <liming.gao@intel.com>
Cc: Qing Huang <qing.huang@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Star Zeng <star.zeng@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>