proc: switch /proc/driver/ray_cs/ray_cs to seq_file interface

Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru>
Cc: Dominik Brodowski <linux@dominikbrodowski.net>
Cc: Jean Tourrilhes <jt@hpl.hp.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Jeff Garzik <jgarzik@pobox.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>