checkpatch: macro complexity checks are meaningless in linker scripts

Exclude vmlinux.lds.h from the macro complexity checks.  They will never
apply sanely here.

Signed-off-by: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>