mmc: renesas_sdhi: initialize variable properly when tuning

'cmd_error' is not necessarily initialized on some error paths in
mmc_send_tuning(). Initialize it.

Fixes: 2c9017d0 ("mmc: renesas_sdhi: abort tuning when timeout detected")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20211130132309.18246-1-wsa+renesas@sang-engineering.comSigned-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/renesas_sdhi_core.c

@@ -673,7 +673,7 @@ static int renesas_sdhi_execute_tuning(struct mmc_host *mmc, u32 opcode)
 
 	/* Issue CMD19 twice for each tap */
 	for (i = 0; i < 2 * priv->tap_num; i++) {
-		int cmd_error;
+		int cmd_error = 0;
 
 		/* Set sampling clock position */
 		sd_scc_write32(host, priv, SH_MOBILE_SDHI_SCC_TAPSET, i % priv->tap_num);