ath10k: remove redundant error check

The check on ret for an error is redundant because it is already been
checked for non-zero earlier on and ret is never non-zero at this point.
Fix this by removing the redundant check and error message.

Detected by CoverityScan, CID#1357170 ("Logically Dead Code")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

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

@@ -970,12 +970,6 @@ static int ath10k_pci_diag_read_mem(struct ath10k *ar, u32 address, void *data,
 		}
 
 		remaining_bytes -= nbytes;
-
-		if (ret) {
-			ath10k_warn(ar, "failed to read diag value at 0x%x: %d\n",
-				    address, ret);
-			break;
-		}
 		memcpy(data, data_buf, nbytes);
 
 		address += nbytes;