wl12xx: move hardcoded hci_io_ds value into the conf struct

Instead of hardcoding the hci_io_ds configuration that we write to the
SDIO_IO_DS top registed, read it from the default configuration so
that it's easier to change for different platforms.

Reported-by: Ido Yariv <ido@wizery.com>
Signed-off-by: Luciano Coelho <coelho@ti.com>
diff --git a/drivers/net/wireless/wl12xx/main.c b/drivers/net/wireless/wl12xx/main.c
index a5a5d01..732fd21 100644
--- a/drivers/net/wireless/wl12xx/main.c
+++ b/drivers/net/wireless/wl12xx/main.c
@@ -319,6 +319,7 @@
 		.min_req_rx_blocks            = 22,
 		.tx_min                       = 27,
 	},
+	.hci_io_ds = HCI_IO_DS_6MA,
 };
 
 static void __wl1271_op_remove_interface(struct wl1271 *wl);