RFC: ANDROID: arm64: vdso: llvm linker does not support -n option

  LD      arch/arm64/kernel/vdso/vdso.so.dbg
ld.lld: error: unknown argument: -n
arch/arm64/kernel/vdso/Makefile:36: recipe for target 'arch/arm64/kernel/vdso/vdso.so.dbg' failed
make[1]: *** [arch/arm64/kernel/vdso/vdso.so.dbg] Error 1
arch/arm64/Makefile:166: recipe for target 'vdso_prepare' failed
make: *** [vdso_prepare] Error 2

Signed-off-by: Amit Pundir <amit.pundir@linaro.org>