mmc: dw_mmc-hi3798mv200: Remove unneeded assignment

The err is being set to 0 and replaced every time after this
assignment. Remove this assignment as it is extraneous.
Signed-off-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20240307122129.2359553-1-usama.anjum@collabora.comSigned-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/dw_mmc-hi3798mv200.c

@@ -133,7 +133,6 @@ static int dw_mci_hi3798mv200_execute_tuning_mix_mode(struct dw_mci_slot *slot,
 			goto tuning_out;
 
 		prev_err = err;
-		err = 0;
 	}
 
 tuning_out: