fs/proc/consoles.c: use seq_putc() in show_console_dev()

A single character (line break) should be put into a sequence.  Thus use
the corresponding function "seq_putc".

This issue was detected by using the Coccinelle software.

Link: http://lkml.kernel.org/r/04fb69fe-d820-9141-820f-07e9a48f4635@users.sourceforge.net


Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>