scsi: wd719x: make card_types static const, shrinks object size

scsi: wd719x: make card_types static const, shrinks object size

Don't populate the read-only array card_types on the stack but instead
make it static and constify it. Makes the object code smaller by over
110 bytes:

Before:
   text	   data	    bss	    dec	    hex	filename
  25625	   5752	      0	  31377	   7a91	drivers/scsi/wd719x.o

After:
   text	   data	    bss	    dec	    hex	filename
  25447	   5816	      0	  31263	   7a1f	drivers/scsi/wd719x.o

(gcc version 7.2.0 x86_64)

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>