MdeModulePkg/DxeIpl: Remove clearing CR0.WP when protecting pagetable

MdeModulePkg/DxeIpl: Remove clearing CR0.WP when protecting pagetable

Remove clearing CR0.WP when marking the memory used for page table
as read-only in the page table itself created by DxeIpl. This page
table address is written to Cr3 after these protection steps. Till
this, the memory used for page table is always RW.

Signed-off-by: Dun Tan <dun.tan@intel.com>
Cc: Dandan Bi <dandan.bi@intel.com>
Cc: Liming Gao <gaoliming@byosoft.com.cn>
Reviewed-by: Ray Ni <ray.ni@intel.com>