Only pre-allocate 256 bytes of cardbio IO range

It may seem small, but most cards need much less, if any, and this not
only makes the code adhere to the comment, it seems to fix a boot-time
lockup on a ThinkPad 380XD laptop reported by Tero Roponen <teanropo@cc.jyu.fi>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

drivers/pci/setup-bus.c

@@ -40,7 +40,7 @@
  * FIXME: IO should be max 256 bytes.  However, since we may
  * have a P2P bridge below a cardbus bridge, we need 4K.
  */
-#define CARDBUS_IO_SIZE		(4096)
+#define CARDBUS_IO_SIZE		(256)
 #define CARDBUS_MEM_SIZE	(32*1024*1024)
 
 static void __devinit