ArmVirtPkg: Move the FdtSerialPortAddressLib to OvmfPkg

Move the FdtSerialPortAddressLib to Ovmfpkg so that other ARCH can
easily use it.

Build-tested only (with "ArmVirtQemu.dsc and OvmfPkgX64.dsc").

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=4584

Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Leif Lindholm <quic_llindhol@quicinc.com>
Cc: Sami Mujawar <sami.mujawar@arm.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Signed-off-by: Chao Li <lichao@loongson.cn>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>

OvmfPkg/OvmfPkg.dec

@@ -29,6 +29,10 @@
   ##  @libraryclass  Verify blobs read from the VMM
   BlobVerifierLib|Include/Library/BlobVerifierLib.h
 
+  ##  @libraryclass  FdtSerialPortAddressLib
+  #
+  FdtSerialPortAddressLib|Include/Library/FdtSerialPortAddressLib.h
+
   ##  @libraryclass  Loads and boots a Linux kernel image
   #
   LoadLinuxLib|Include/Library/LoadLinuxLib.h