MdePkg/Include: LoongArch definitions.

MdePkg/Include: LoongArch definitions.

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

Add LoongArch processor related definitions.

For the Http boot and PXE boot types seeing this URL section "Processor
Architecture Type" for the LOONGARCH values:
https://www.iana.org/assignments/dhcpv6-parameters/dhcpv6-parameters.xhtml

For definitions of PE/COFF and LOONGARCH relocation types, see the
"Machine Types" and "Basic Relocation Types" sections of this URL for
LOONGARCH values:
https://docs.microsoft.com/en-us/windows/win32/debug/pe-format

For the register definitions of exceptions context, see the UEFI V2.10
18.2.2, 18.2.4 and 18.2.5 sections of this URL for LOONGARCH
definitions:
https://uefi.org/specs/UEFI/2.10/18_Protocols_Debugger_Support.html

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>
Reviewed-by: Michael D Kinney <michael.d.kinney@intel.com>
Reviewed-by: Liming Gao <gaoliming@byosoft.com.cn>