MdePkg/BaseRngLib: Remove global variable for RDRAND state update

As a BASE type library, some PEI drivers could link and use it.
Tcg2Pei.inf is an example. On edk2-stable202408 version, PEI drivers
that link the library include the global variable of mRdRandSupported.
The previous commit (c3a8ca7) that refers to the global variable actually
is found to influence the link status. Updating the global variable
in PEI drivers could affect the following issues.

PEI ROM Boot : Global variable is not updated
PEI RAM Boot : PEI FV integration/security check is failed

To address these issues, remove the global variable usage.

Signed-off-by: Phil Noh <Phil.Noh@amd.com>

Author: philnoh2

MdePkg/Library/BaseRngLib/Rand/RdRand.c

@@ -2,6 +2,7 @@
   Random number generator services that uses RdRand instruction access
   to provide high-quality random numbers.
 
+Copyright (C) 2024 Advanced Micro Devices, Inc. All rights reserved.<BR>
 Copyright (c) 2023, Arm Limited. All rights reserved.<BR>
 Copyright (c) 2022, Pedro Falcato. All rights reserved.<BR>
 Copyright (c) 2021, NUVIA Inc. All rights reserved.<BR>
@@ -23,8 +24,6 @@ SPDX-License-Identifier: BSD-2-Clause-Patent
 //
 #define RDRAND_MASK  BIT30
 
-STATIC BOOLEAN  mRdRandSupported;
-
 //
 // Intel SDM says 10 tries is good enough for reliable RDRAND usage.
 //
@@ -124,20 +123,6 @@ BaseRngLibConstructor (
   VOID
   )
 {
-  UINT32  RegEcx;
-
-  //
-  // Determine RDRAND support by examining bit 30 of the ECX register returned by
-  // CPUID. A value of 1 indicates that processor support RDRAND instruction.
-  //
-  AsmCpuid (1, 0, 0, &RegEcx, 0);
-
-  mRdRandSupported = ((RegEcx & RDRAND_MASK) == RDRAND_MASK);
-
-  if (mRdRandSupported) {
-    mRdRandSupported = TestRdRand ();
-  }
-
   return EFI_SUCCESS;
 }
 
@@ -156,7 +141,6 @@ ArchGetRandomNumber16 (
   OUT     UINT16  *Rand
   )
 {
-  ASSERT (mRdRandSupported);
   return AsmRdRand16 (Rand);
 }
 
@@ -175,7 +159,6 @@ ArchGetRandomNumber32 (
   OUT     UINT32  *Rand
   )
 {
-  ASSERT (mRdRandSupported);
   return AsmRdRand32 (Rand);
 }
 
@@ -194,7 +177,6 @@ ArchGetRandomNumber64 (
   OUT     UINT64  *Rand
   )
 {
-  ASSERT (mRdRandSupported);
   return AsmRdRand64 (Rand);
 }
 
@@ -211,7 +193,22 @@ ArchIsRngSupported (
   VOID
   )
 {
-  return mRdRandSupported;
+  BOOLEAN  RdRandSupported;
+  UINT32   RegEcx;
+
+  //
+  // Determine RDRAND support by examining bit 30 of the ECX register returned by
+  // CPUID. A value of 1 indicates that processor support RDRAND instruction.
+  //
+  AsmCpuid (1, 0, 0, &RegEcx, 0);
+
+  RdRandSupported = ((RegEcx & RDRAND_MASK) == RDRAND_MASK);
+
+  if (RdRandSupported) {
+    RdRandSupported = TestRdRand ();
+  }
+
+  return RdRandSupported;
 }
 
 /**