Staging: slicoss: Replace seq_printf with seq_puts

This patch fixes the following checkpatch.pl warning in slicoss.c:
WARNING: Prefer seq_puts to seq_printf

Signed-off-by: Rashika Kheria <rashika.kheria@gmail.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>