OvmfPkg/BaseCachingPciExpressLib: Migrate BaseCachingPciExpressLib

Move BaseCachingPciExpressLib library from ArmVirtPkg to under OvmfPkg.
RISC-V Virt platform can leverage the same library to access PCI Express
registers through PCI Express base address set in PcdPciExpressBaseAddress
and cached in a global variable.

Cc: Daniel Schaefer <daniel.schaefer@hpe.com>
Cc: Sunil V L <sunilvl@ventanamicro.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Abner Chang <abner.chang@hpe.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>

OvmfPkg/Library/BaseCachingPciExpressLib/BaseCachingPciExpressLib.inf

@@ -0,0 +1,42 @@
+## @file
+#  Instance of PCI Express Library using the 256 MB PCI Express MMIO window.
+#
+#  PCI Express Library that uses the 256 MB PCI Express MMIO window to perform
+#  PCI Configuration cycles. Layers on top of an I/O Library instance.
+#
+#  Copyright (c) 2007 - 2014, Intel Corporation. All rights reserved.<BR>
+#
+#  SPDX-License-Identifier: BSD-2-Clause-Patent
+#
+#
+##
+
+[Defines]
+  INF_VERSION                    = 0x00010005
+  BASE_NAME                      = BaseCachingPciExpressLib
+  FILE_GUID                      = 3f3ffd80-04dc-4a2b-9d25-ecca55c2e520
+  MODULE_TYPE                    = BASE
+  VERSION_STRING                 = 1.0
+  LIBRARY_CLASS                  = PciExpressLib|DXE_DRIVER UEFI_DRIVER UEFI_APPLICATION
+  CONSTRUCTOR                    = PciExpressLibInitialize
+
+#
+#  VALID_ARCHITECTURES           = ARM AARCH64 RISCV64
+#
+
+[Sources]
+  PciExpressLib.c
+
+[Packages]
+  MdePkg/MdePkg.dec
+
+[LibraryClasses]
+  BaseLib
+  PcdLib
+  DebugLib
+  IoLib
+  PciPcdProducerLib
+
+[Pcd]
+  gEfiMdePkgTokenSpaceGuid.PcdPciExpressBaseAddress  ## CONSUMES
+