Added the PEI stage library for QemuFwCfgMmioLib, which uses the FDT to
find the fw_cfg and parse it.
BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=4755
Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Co-authored-by: Xianglai Li <lixianglai@loongson.cn>
Signed-off-by: Chao Li <lichao@loongson.cn>
Chao Li