MdePkg: Replace Opcode with the corresponding instructions.

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=3790

Replace Opcode with the corresponding instructions.
The code changes have been verified with CompareBuild.py tool, which
can be used to compare the results of two different EDK II builds to
determine if they generate the same binaries.
(tool link: https://github.com/mdkinney/edk2/tree/sandbox/CompareBuild)

Signed-off-by: Jason Lou <yun.lou@intel.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Reviewed-by: Liming Gao <gaoliming@byosoft.com.cn>
Cc: Zhiguang Liu <zhiguang.liu@intel.com>

MdePkg/Library/BaseLib/X64/DisablePaging64.nasm

@@ -1,6 +1,6 @@
 ;------------------------------------------------------------------------------
 ;
-; Copyright (c) 2006 - 2008, Intel Corporation. All rights reserved.<BR>
+; Copyright (c) 2006 - 2022, Intel Corporation. All rights reserved.<BR>
 ; SPDX-License-Identifier: BSD-2-Clause-Patent
 ;
 ; Module Name:
@@ -51,8 +51,7 @@ ASM_PFX(InternalX86DisablePaging64):
     sub     eax, 4                      ; eax <- One slot below transition code on the stack
     push    rcx                         ; push Cs to stack
     push    r10                         ; push address of tansition code on stack
-    DB      0x48                         ; prefix to composite "retq" with next "retf"
-    retf                                ; Use far return to load CS register from stack
+    retfq
 
 ; Start of transition code
 .0: