[SCSI] Fix sense key MEDIUM ERROR processing and retry

1) If the device reports an uncorrectable MEDIUM ERROR, such
as SK MEDIUM ERROR, ASC UNRECOVERED READ ERR, AMNF DATA
FIELD or RECORD NOT FOUND, then: In scsi_check_sense()
return SUCCESS so as to not retry -- the error is
uncorrectable -- this speeds up total processing time.
Signed-off-by: Luben Tuikov <ltuikov@yahoo.com>

Extracted the MEDIUM ERROR piece and
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

drivers/scsi/scsi_error.c

@@ -359,6 +359,11 @@ static int scsi_check_sense(struct scsi_cmnd *scmd)
 		return SUCCESS;
 
 	case MEDIUM_ERROR:
+		if (sshdr.asc == 0x11 || /* UNRECOVERED READ ERR */
+		    sshdr.asc == 0x13 || /* AMNF DATA FIELD */
+		    sshdr.asc == 0x14) { /* RECORD NOT FOUND */
+			return SUCCESS;
+		}
 		return NEEDS_RETRY;
 
 	case HARDWARE_ERROR: