CHROMIUM: mmc: sdio: Disable retuning in sdio_reset_comm()

Since sdio_reset_comm() re-initializes the SDIO card, disable retuning
before idling and shutting down the card.  Tuning will be re-enabled (if
necessary) in mmc_sdio_init_card().

BUG=chrome-os-partner:46444
TEST=With CL:311815, toggle WiFi on/off on Smaug and observe that the
WiFi card comes back up and is able to tune successfully.

Change-Id: Ib4a5cfd4d75fc9e3ed7bb3f1e2ffd30de16c5d28
Signed-off-by: Andrew Bresticker <abrestic@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/311797
Reviewed-by: Derek Basehore <dbasehore@chromium.org>

drivers/mmc/core/sdio.c

@@ -22,6 +22,7 @@
 
 #include "core.h"
 #include "bus.h"
+#include "host.h"
 #include "sd.h"
 #include "sdio_bus.h"
 #include "mmc_ops.h"
@@ -1225,6 +1226,8 @@ int sdio_reset_comm(struct mmc_card *card)
 	printk("%s():\n", __func__);
 	mmc_claim_host(host);
 
+	mmc_retune_disable(host);
+
 	mmc_go_idle(host);
 
 	mmc_set_clock(host, host->f_min);