ath10k: fix possible memory leak in ath10k_bmi_lz_data_large()

'cmd' is malloced in ath10k_bmi_lz_data_large() and should be freed
before leaving from the error handling cases, otherwise it will cause
memory leak.

Fixes: d58f466a ("ath10k: add large size for BMI download data for SDIO")
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20200427104348.13570-1-weiyongjun1@huawei.com

drivers/net/wireless/ath/ath10k/bmi.c

@@ -380,6 +380,7 @@ static int ath10k_bmi_lz_data_large(struct ath10k *ar, const void *buffer, u32 l
 						  NULL, NULL);
 		if (ret) {
 			ath10k_warn(ar, "unable to write to the device\n");
+			kfree(cmd);
 			return ret;
 		}