MdeModulePkg/PiSmmCore: AllocatePool should use MemoryType.

MdeModulePkg/PiSmmCore: AllocatePool should use MemoryType.

PiSmmCore supports page level protection based upon the Memory Type
(EfiRuntimeServicesCode/EfiRuntimeServicesData) and PE image.

However, the Memory Type information is ignored in AllocatePool().
If a caller calls AllocatePool with EfiRuntimeServicesCode,
the final memory is still allocated as EfiRuntimeServicesData.

This patch supports AllocatePool with EfiRuntimeServicesCode.

Cc: Jeff Fan <jeff.fan@intel.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Jiewen Yao <jiewen.yao@intel.com>
Reviewed-by: Jeff Fan <jeff.fan@intel.com>
Regression-tested-by: Laszlo Ersek <lersek@redhat.com>