romfs_strnlen() returns int
unsigned X >= 0 is always true

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: roel kluin <roel.kluin@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>