payloads/edk2: Only pass IA32 argument

With the coreboot build process, `UniversalPayloadBuild.sh` calls
`UniversalPayloadBuild.py`. That Python script will unconditionally
build DXE as 64-bit, but accepts an argument for the entry point:
    parser.add_argument('-a', '--Arch', choices=['IA32', 'X64'],
    help='Specify the ARCH for payload entry module. Default build X64
    image.', default ='X64')

Currently, ` -a IA32 -a X64` is passed, and the Python script will
use the `X64` argument, resulting in a payload that won't work with
coreboot.

Remove the `-a X64`, so the resulting build is a 32-bit entry point,
and 64-bit DXE, which works with coreboot.

Signed-off-by: Sean Rhodes <sean@starlabs.systems>
Change-Id: I8a557d6e155a2938b44036d98f9274cc8b38f156
Reviewed-on: https://review.coreboot.org/c/coreboot/+/73668
Reviewed-by: Matt DeVillier <matt.devillier@gmail.com>
Reviewed-by: Paul Menzel <paulepanter@mailbox.org>
Reviewed-by: Martin L Roth <gaumless@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Benjamin Doron <benjamin.doron00@gmail.com>
Reviewed-by: Felix Singer <service+coreboot-gerrit@felixsinger.de>
Reviewed-by: Patrick Rudolph <patrick.rudolph@9elements.com>

payloads/external/edk2/Makefile

@@ -247,7 +247,7 @@ $(WORKSPACE)/Build/UefiPayloadPkgX64/UniversalPayload.elf: \
 	cd $(WORKSPACE); \
 		source $(EDK2_PATH)/edksetup.sh; \
 		echo -n "EDK2: Building... "; \
-		$(EDK2_PATH)/UefiPayloadPkg/UniversalPayloadBuild.sh -a IA32 -a X64 -b $(RELEASE_STR) $(BUILD_STR)
+		$(EDK2_PATH)/UefiPayloadPkg/UniversalPayloadBuild.sh -a IA32 -b $(RELEASE_STR) $(BUILD_STR)
 		if [ ! -f $@ ]; then \
 			echo "Failed!"; \
 			exit 1; \