ath10k: provide errno if bmi read/write fails

Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>
diff --git a/drivers/net/wireless/ath/ath10k/bmi.c b/drivers/net/wireless/ath/ath10k/bmi.c
index 1a2ef51..aeae029 100644
--- a/drivers/net/wireless/ath/ath10k/bmi.c
+++ b/drivers/net/wireless/ath/ath10k/bmi.c
@@ -105,7 +105,8 @@
 		ret = ath10k_hif_exchange_bmi_msg(ar, &cmd, cmdlen,
 						  &resp, &rxlen);
 		if (ret) {
-			ath10k_warn("unable to read from the device\n");
+			ath10k_warn("unable to read from the device (%d)\n",
+				    ret);
 			return ret;
 		}
 
@@ -149,7 +150,8 @@
 		ret = ath10k_hif_exchange_bmi_msg(ar, &cmd, hdrlen + txlen,
 						  NULL, NULL);
 		if (ret) {
-			ath10k_warn("unable to write to the device\n");
+			ath10k_warn("unable to write to the device (%d)\n",
+				    ret);
 			return ret;
 		}