LoongArch: Adjust VDSO/VSYSCALL for 32BIT/64BIT

Adjust VDSO/VSYSCALL because read_cpu_id() for 32BIT/64BIT are
different, and LoongArch32 doesn't support GENERIC_GETTIMEOFDAY now
(will be supported in future).

Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

arch/loongarch/vdso/Makefile

@@ -4,8 +4,9 @@
 # Include the generic Makefile to check the built vdso.
 include $(srctree)/lib/vdso/Makefile.include
 
-obj-vdso-y := elf.o vgetcpu.o vgettimeofday.o vgetrandom.o \
+obj-vdso-y := elf.o vgetcpu.o vgetrandom.o \
               vgetrandom-chacha.o sigreturn.o
+obj-vdso-$(CONFIG_GENERIC_GETTIMEOFDAY) += vgettimeofday.o
 
 # Common compiler flags between ABIs.
 ccflags-vdso := \
@@ -16,6 +17,10 @@ ccflags-vdso := \
 	$(CLANG_FLAGS) \
 	-D__VDSO__
 
+ifdef CONFIG_32BIT
+ccflags-vdso += -DBUILD_VDSO32
+endif
+
 cflags-vdso := $(ccflags-vdso) \
 	-isystem $(shell $(CC) -print-file-name=include) \
 	$(filter -W%,$(filter-out -Wa$(comma)%,$(KBUILD_CFLAGS))) \