ray_cs: Use static const

Using static const generally increases object text and decreases data size.
It also generally decreases overall object size.

   text	   data	    bss	    dec	    hex	filename
  42607	   3581	   8536	  54724	   d5c4	drivers/net/wireless/ray_cs.o.new
  42603	   3585	   8536	  54724	   d5c4	drivers/net/wireless/ray_cs.o.old

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>