mmc: mmc_spi: correct the while condition

When variable i will become 0, while(i--) loop breaks but variable i will
again decrement to -1 because of i-- and that's why below condition
"if (!i && (r != resp_match_value)" will never execute, So doing "i--"
inside of while() loop solves this problem.

Signed-off-by: Pragnesh Patel <pragnesh.patel@sifive.com>
Reviewed-by: Bin Meng <bin.meng@windriver.com>
Tested-by: Bin Meng <bin.meng@windriver.com>
diff --git a/drivers/mmc/mmc_spi.c b/drivers/mmc/mmc_spi.c
index e76ab54..86cc932 100644
--- a/drivers/mmc/mmc_spi.c
+++ b/drivers/mmc/mmc_spi.c
@@ -105,12 +105,14 @@
 	if (resp_match) {
 		r = ~resp_match_value;
 		i = CMD_TIMEOUT;
-		while (i--) {
+		while (i) {
 			ret = dm_spi_xfer(dev, 1 * 8, NULL, &r, 0);
 			if (ret)
 				return ret;
 			debug(" resp%d=0x%x", rpos, r);
 			rpos++;
+			i--;
+
 			if (r == resp_match_value)
 				break;
 		}