mmc: core: properly init drv_type

When the latest version of parsing the new eMMC bindings was moved from
core.c to mmc.c, it was overlooked that drv_type could be used
uninitialized. Fix it!

Fixes: 6186d06c ("mmc: parse new binding for eMMC fixed driver type")
Reported-by: Colin Ian King <colin.king@canonical.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/core/mmc.c

@@ -1290,7 +1290,7 @@ int mmc_hs400_to_hs200(struct mmc_card *card)
 
 static void mmc_select_driver_type(struct mmc_card *card)
 {
-	int card_drv_type, drive_strength, drv_type;
+	int card_drv_type, drive_strength, drv_type = 0;
 	int fixed_drv_type = card->host->fixed_drv_type;
 
 	card_drv_type = card->ext_csd.raw_driver_strength |