scsi: replace seq_printf with seq_puts

Using seq_printf to print a simple string is a lot more expensive than
it needs to be, since seq_puts exists. Replace seq_printf with
seq_puts when possible.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Reviewed-by: Finn Thain <fthain@telegraphics.com.au>
Signed-off-by: Christoph Hellwig <hch@lst.de>