RapidIO: Fix comment error.

The resource index for the mailboxes was incorrect.

Signed-off-by: Chad Reese <kreese@caviumnetworks.com>
Acked-by: Alexandre Bounine <alexandre.bounine@idt.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

include/linux/rio.h

@@ -62,7 +62,7 @@
  *
  *	0	RapidIO inbound doorbells
  *	1	RapidIO inbound mailboxes
- *	1	RapidIO outbound mailboxes
+ *	2	RapidIO outbound mailboxes
  */
 #define RIO_DOORBELL_RESOURCE	0
 #define RIO_INB_MBOX_RESOURCE	1