The self-test was updated to cover zero-length strings; the function
needs to be updated, too.
Reported-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: NGeorge Spelvin <linux@sciencehorizons.net>
Fixes: fcfd2fbf ("fs/namei.c: Add hashlen_string() function")
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>