LoongArch: vDSO: Disable UBSAN instrumentation

The vDSO executes in userspace, so the kernel's UBSAN should not
instrument it. Solves these kind of build errors:

  loongarch64-linux-ld: arch/loongarch/vdso/vgettimeofday.o: in function `vdso_shift_ns':
  lib/vdso/gettimeofday.c:23:(.text+0x3f8): undefined reference to `__ubsan_handle_shift_out_of_bounds'

Reported-by: kernel test robot <[email protected]>
Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/
Cc: Huacai Chen <[email protected]>
Cc: WANG Xuerui <[email protected]>
Cc: Vincenzo Frascino <[email protected]>
Cc: Nathan Chancellor <[email protected]>
Cc: Masahiro Yamada <[email protected]>
Cc: Fangrui Song <[email protected]>
Cc: [email protected]
Signed-off-by: Kees Cook <[email protected]>
Signed-off-by: Huacai Chen <[email protected]>

Author: kees

arch/loongarch/vdso/Makefile

@@ -2,6 +2,7 @@
 # Objects to go into the VDSO.
 
 KASAN_SANITIZE := n
+UBSAN_SANITIZE := n
 KCOV_INSTRUMENT := n
 
 # Include the generic Makefile to check the built vdso.