MdeModulePkg PeiCore: Recheck SwitchStackSignal after ProcessNotifyList()

MdeModulePkg PeiCore: Recheck SwitchStackSignal after ProcessNotifyList()

in case PeiInstallPeiMemory() is done in a callback with
EFI_PEI_PPI_DESCRIPTOR_NOTIFY_DISPATCH, and the callback is registered on
a PPI that is installed in the last PEIM.

At the case, PeiCore SwitchStack code will be not being invoked.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Star Zeng <star.zeng@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18305 6f19259b-4bc3-4df7-8a09-765794883524