fs/proc/task_mmu.c: replace seq_printf by seq_puts

Signed-off-by: Fabian Frederick <fabf@skynet.be>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>