mmc: zynq: Fix default value for xlnx,mio-bank

DT binding is saying that default value is 0 not -1 that's why fix it.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Acked-by: Peng Fan <peng.fan@nxp.com>

diff --git a/drivers/mmc/zynq_sdhci.c b/drivers/mmc/zynq_sdhci.c
index 6505527..e9381b9 100644
--- a/drivers/mmc/zynq_sdhci.c
+++ b/drivers/mmc/zynq_sdhci.c
@@ -276,7 +276,7 @@
 		return PTR_ERR(priv->host->ioaddr);
 
 	priv->deviceid = dev_read_u32_default(dev, "xlnx,device_id", -1);
-	priv->bank = dev_read_u32_default(dev, "xlnx,mio-bank", -1);
+	priv->bank = dev_read_u32_default(dev, "xlnx,mio-bank", 0);
 
 	return 0;
 }