wl1251: fix ELP_CTRL register accesses when using SDIO

For some unknown reason ELP_CTRL can't be accesed using
sdio_memcpy_* functions (any attemts to do so result in timeouts):

 wl1251: ERROR sdio write failed (-110)
 wl1251: ERROR sdio read failed (-110)
 wl1251: WARNING WLAN not ready

To fix this, add special IO functions for ELP_CTRL access that are
using sdio_readb/sdio_writeb. Similar handling is done in TI
reference driver from Android code drop.

Signed-off-by: Grazvydas Ignotas <notasas@gmail.com>
Cc: Bob Copeland <me@bobcopeland.com>
Acked-by: Kalle Valo <kalle.valo@iki.fi>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/wl12xx/wl1251.h b/drivers/net/wireless/wl12xx/wl1251.h
index 37c61c1..4f5f02a 100644
--- a/drivers/net/wireless/wl12xx/wl1251.h
+++ b/drivers/net/wireless/wl12xx/wl1251.h
@@ -256,6 +256,8 @@
 struct wl1251_if_operations {
 	void (*read)(struct wl1251 *wl, int addr, void *buf, size_t len);
 	void (*write)(struct wl1251 *wl, int addr, void *buf, size_t len);
+	void (*read_elp)(struct wl1251 *wl, int addr, u32 *val);
+	void (*write_elp)(struct wl1251 *wl, int addr, u32 val);
 	void (*reset)(struct wl1251 *wl);
 	void (*enable_irq)(struct wl1251 *wl);
 	void (*disable_irq)(struct wl1251 *wl);