i2c: qup: Fix wrong value of index variable

index gets incremented during check to determine if the
messages can be transferred with dma. But not reset after
that, resulting in wrong start value in subsequent loop,
causing failure. Fix it.
Signed-off-by: Sricharan R <sricharan@codeaurora.org>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Cc: stable@kernel.org

drivers/i2c/busses/i2c-qup.c

@@ -1268,6 +1268,8 @@ static int qup_i2c_xfer_v2(struct i2c_adapter *adap,
 		}
 	}
 
+	idx = 0;
+
 	do {
 		if (msgs[idx].len == 0) {
 			ret = -EINVAL;