drivers/video/aty/aty128fb.c: fix incorrect usage of strncat in aty128_init()

Fix incorrect length for strncat by replacing it with strlcat

Signed-off-by: Roel Kluin <12o3l@tiscali.nl>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>