BaseTools/GenFds: Apply OEM_CAPSULE_FLAGS during Capsule generation.

Bugzilla ticket 4633

FdfParser.py has defined a key named OEM_CAPSULE_FLAGS to set the
lower 16 bits of EFI_CAPSULE_HEADER.Flags. However, this key is totally
"forgotten" in Capsule.py, making it impossible to set lower 16 bits of
this field, and leading to an always FALSE when comparing to
gEfiMdeModulePkgTokenSpaceGuid.PcdSystemRebootAfterCapsuleProcessFlag
in MdeModulePkg/Library/DxeCapsuleLibFmp/DxeCapsuleProcessLib.c:
ProcessTheseCapsules().

This patch ORs the value of OEM_CAPSULE_FLAGS with previously calculated
CAPSULE_FLAGS value, making the lower 16 bits of value being correctly set.

Signed-off-by: Igniculus Fu <igniculus.fu@amd.com>
Cc: Bob Feng <bob.c.feng@intel.com>
Cc: Liming Gao <gaoliming@byosoft.com.cn>
Cc: Yuwei Chen <yuwei.chen@intel.com>
Cc: Abner Chang <abner.chang@amd.com>
Cc: Eric Xing <eric.xing@amd.com>
Cc: Abdul Lateef Attar <abdattar@amd.com>
Reviewed-by: Liming Gao <gaoliming@byosoft.com.cn>

BaseTools/Source/Python/GenFds/Capsule.py

@@ -1,6 +1,7 @@
 ## @file
 # generate capsule
 #
+#  Copyright (C) 2024 Advanced Micro Devices, Inc. All rights reserved.<BR>
 #  Copyright (c) 2007 - 2018, Intel Corporation. All rights reserved.<BR>
 #
 #  SPDX-License-Identifier: BSD-2-Clause-Patent
@@ -78,6 +79,8 @@ class Capsule (CapsuleClassObject):
                     Flags |= 0x00010000
                 elif flag == 'InitiateReset':
                     Flags |= 0x00040000
+        if 'OEM_CAPSULE_FLAGS' in self.TokensDict:
+            Flags |= int(self.TokensDict['OEM_CAPSULE_FLAGS'],16)
         Header.write(pack('=I', Flags))
         #
         # typedef struct {