MdePkg: Add LoongArch LOONGARCH64 binding

MdePkg: Add LoongArch LOONGARCH64 binding

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=4053

Add LOONGARCH64 sections in MdePkg.dec and LOONGARCH64 ProcessorBind.h

Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Liming Gao <gaoliming@byosoft.com.cn>
Cc: Zhiguang Liu <zhiguang.liu@intel.com>
Signed-off-by: Chao Li <lichao@loongson.cn>
Co-authored-by: Baoqi Zhang <zhangbaoqi@loongson.cn>
Co-authored-by: Dongyan Qian <qiandongyan@loongson.cn>
Reviewed-by: Michael D Kinney <michael.d.kinney@intel.com>