pcmcia: Convert pcmcia_device_id declarations to const

Saves about 50KB of data.

Old/new size of all objects:
   text	   data	    bss	    dec	    hex	filename
 563015	  80096	 130684	 773795	  bcea3	(TOTALS)
 610916	  32256	 130632	 773804	  bceac	(TOTALS)

Signed-off-by: Joe Perches <joe@perches.com>
Acked-by: Kurt Van Dijck <kurt.van.dijck@eia.be> (for drivers/net/can/softing/softing_cs.c)
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>