checkpatch: suppress errors triggered by short patch

When the last hunk of a patch is short it will trigger errors from
checkpatch:

    Use of uninitialized value in pattern match (m//)
	    at /usr/local/bin/checkpatch.pl line 394.
    Use of uninitialized value in concatenation (.) or string
	    at /usr/local/bin/checkpatch.pl line 397.
    Use of uninitialized value in pattern match (m//)

Avoid touching beyond the last line.  Reported by Julien Brunel.

Signed-off-by: Andy Whitcroft <apw@shadowen.org>
Cc: Julien Brunel <brunel@diku.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>