scsi: target: fix spelling mistake "Uknown" -> "Unknown"

Trivial fix to spelling mistake in pr_err message text.
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/target/target_core_transport.c

@@ -3366,7 +3366,7 @@ static void target_tmr_work(struct work_struct *work)
 		tmr->response = TMR_FUNCTION_REJECTED;
 		break;
 	default:
-		pr_err("Uknown TMR function: 0x%02x.\n",
+		pr_err("Unknown TMR function: 0x%02x.\n",
 				tmr->function);
 		tmr->response = TMR_FUNCTION_REJECTED;
 		break;