wl1251: separate bus i/o code into io.c

In order to eventually support wl1251 spi and sdio interfaces, move
the register and memory transfer functions to a common file.  Also
rename wl1251_spi_mem_{read,write} to indicate its common usage.
We still use spi_read internally until SDIO interface is introduced
so nothing functional should change here.

Signed-off-by: Bob Copeland <me@bobcopeland.com>
Signed-off-by: Kalle Valo <kalle.valo@nokia.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/wl12xx/wl1251_event.c

@@ -24,7 +24,7 @@
 
 #include "wl1251.h"
 #include "reg.h"
-#include "wl1251_spi.h"
+#include "wl1251_io.h"
 #include "wl1251_event.h"
 #include "wl1251_ps.h"
 
@@ -112,7 +112,7 @@ int wl1251_event_handle(struct wl1251 *wl, u8 mbox_num)
 		return -EINVAL;
 
 	/* first we read the mbox descriptor */
-	wl1251_spi_mem_read(wl, wl->mbox_ptr[mbox_num], &mbox,
+	wl1251_mem_read(wl, wl->mbox_ptr[mbox_num], &mbox,
 			    sizeof(struct event_mailbox));
 
 	/* process the descriptor */