ArmVirtPkg/QemuFwCfgLib: Relocate QemuFwCfgLib to OvmfPkg

Relocate QemuFwCfgLib to OvmfPkg/Library/QemuFwCfgLib and rename
it to QemuFwCfgLibMmio, this library is leverage by both ARM and
RISC-V archs.

Signed-off-by: Abner Chang <abner.chang@hpe.com>
Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
Cc: Leif Lindholm <leif@nuviainc.com>
Cc: Sami Mujawar <sami.mujawar@arm.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Daniel Schaefer <daniel.schaefer@hpe.com>
Cc: Sunil V L <sunilvl@ventanamicro.com>
Reviewed-by: Daniel Schaefer <daniel.schaefer@hpe.com>
Reviewed-by: Sunil V L <sunilvl@ventanamicro.com>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>
Acked-by: Jiewen Yao <jiewen.yao@intel.com>

OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgLibMmio.inf

@@ -0,0 +1,48 @@
+## @file
+#
+#  Stateful, implicitly initialized fw_cfg library.
+#
+#  Copyright (C) 2013 - 2014, Red Hat, Inc.
+#  Copyright (c) 2008 - 2012, Intel Corporation. All rights reserved.<BR>
+#
+#  SPDX-License-Identifier: BSD-2-Clause-Patent
+#
+##
+
+[Defines]
+  INF_VERSION                    = 0x00010005
+  BASE_NAME                      = QemuFwCfgLib
+  FILE_GUID                      = B271F41F-B841-48A9-BA8D-545B4BC2E2BF
+  MODULE_TYPE                    = BASE
+  VERSION_STRING                 = 1.0
+  LIBRARY_CLASS                  = QemuFwCfgLib|DXE_DRIVER UEFI_DRIVER
+
+  CONSTRUCTOR                    = QemuFwCfgInitialize
+
+#
+# The following information is for reference only and not required by the build
+# tools.
+#
+#  VALID_ARCHITECTURES           = ARM AARCH64
+#
+
+[Sources]
+  QemuFwCfgLibMmio.c
+
+[Packages]
+  MdePkg/MdePkg.dec
+  OvmfPkg/OvmfPkg.dec
+  EmbeddedPkg/EmbeddedPkg.dec
+
+[LibraryClasses]
+  BaseLib
+  BaseMemoryLib
+  DebugLib
+  IoLib
+  UefiBootServicesTableLib
+
+[Protocols]
+  gFdtClientProtocolGuid                                ## CONSUMES
+
+[Depex]
+  gFdtClientProtocolGuid