target: tcm_loop: Use seq_puts() in tcm_loop_show_info()

The script "checkpatch.pl" pointed information out like the following.

WARNING: Prefer seq_puts to seq_printf

Thus fix the affected source code place.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>