LoongArch: Specify -m32/-m64 explicitly for 32BIT/64BIT

Clang/LLVM build needs -m32/-m64 to switch triple variants (i.e. the
--target=xxx parameter). Otherwise we get build errors for CONFIG_32BIT.

GCC doesn't support -m32/-m64 now, but maybe support in future, so use
cc-option to specify them.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202604232041.ESJDwVG4-lkp@intel.com/
Suggested-by: Nathan Chancellor <nathan@kernel.org
Tested-by: WANG Rui <wangrui@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

Author: chenhuacai

arch/loongarch/Makefile

@@ -55,9 +55,11 @@ endif
 ifdef CONFIG_32BIT
 tool-archpref		= $(32bit-tool-archpref)
 UTS_MACHINE		:= loongarch32
+cflags-y		+= $(call cc-option,-m32)
 else
 tool-archpref		= $(64bit-tool-archpref)
 UTS_MACHINE		:= loongarch64
+cflags-y		+= $(call cc-option,-m64)
 endif
 
 ifneq ($(SUBARCH),$(ARCH))

arch/loongarch/vdso/Makefile

@@ -12,6 +12,8 @@ obj-vdso-$(CONFIG_GENERIC_GETTIMEOFDAY) += vgettimeofday.o
 ccflags-vdso := \
 	$(filter -I%,$(KBUILD_CFLAGS)) \
 	$(filter -E%,$(KBUILD_CFLAGS)) \
+	$(filter -m32,$(KBUILD_CFLAGS)) \
+	$(filter -m64,$(KBUILD_CFLAGS)) \
 	$(filter -march=%,$(KBUILD_CFLAGS)) \
 	$(filter -m%-float,$(KBUILD_CFLAGS)) \
 	$(CLANG_FLAGS) \