usb: storage: make const arrays static, reduces object code size

Don't populate const arrays on the stack, instead make them
static.  Makes the object code smaller by over 1070 bytes:

Before:
   text	   data	    bss	    dec	    hex	filename
   3505	    880	      0	   4385	   1121	drivers/usb/storage/option_ms.o

After:
   text	   data	    bss	    dec	    hex	filename
   2269	   1040	      0	   3309	    ced	drivers/usb/storage/option_ms.o

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>