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_main.c b/drivers/net/wireless/wl12xx/wl1251_main.c
index 24ae6a3..0155653 100644
--- a/drivers/net/wireless/wl12xx/wl1251_main.c
+++ b/drivers/net/wireless/wl12xx/wl1251_main.c
@@ -146,8 +146,8 @@
 	u32 elp_reg;
 
 	elp_reg = ELPCTRL_WAKE_UP;
-	wl1251_write32(wl, HW_ACCESS_ELP_CTRL_REG_ADDR, elp_reg);
-	elp_reg = wl1251_read32(wl, HW_ACCESS_ELP_CTRL_REG_ADDR);
+	wl1251_write_elp(wl, HW_ACCESS_ELP_CTRL_REG_ADDR, elp_reg);
+	elp_reg = wl1251_read_elp(wl, HW_ACCESS_ELP_CTRL_REG_ADDR);
 
 	if (!(elp_reg & ELPCTRL_WLAN_READY))
 		wl1251_warning("WLAN not ready");