edk2-firmware: Fix 32 builds on ArmVirtQemu

Pass the right target prefix for arm build on both gcc and clang.

Also, add a compatibility symlink path for builds that use arch in the
directory output.

Signed-off-by: Andrei Gherzan <andrei.gherzan@huawei.com>

meta-oniro-staging/recipes-bsp/uefi/edk2-firmware_%.bbappend

+# SPDX-FileCopyrightText: Huawei Inc.
+#
+# SPDX-License-Identifier: Apache-2.0
+
+export GCC5_ARM_PREFIX = "${TARGET_PREFIX}"
+export CLANG38_ARM_PREFIX = "${TARGET_PREFIX}"
+
+do_install:prepend() {
+	# Some platforms use an ARCH suffix.
+	if [ ! -e "${B}/Build/${EDK2_PLATFORM}" ]; then
+		ln -s ${EDK2_PLATFORM}-${EDK2_ARCH} ${B}/Build/${EDK2_PLATFORM}
+	fi
+}