ide: use do_rw_taskfile() for ATA_CMD_PACKET commands

* Pass command to ide_issue_pc() and update ->do_request methods
  in ide-{cd,floppy,tape}.c accordingly.

* Convert ide_pktcmd_tf_load() to ide_init_packet_cmd() which
  just initializes command structure and use do_rw_taskfile()
  to load ATA_CMD_PACKET commands.

While at it:

* Rename ide{floppy,tape}_issue_pc() to ide_{floppy,tape}_issue_pc().

There should be no functional changes caused by this patch.

Acked-by: Borislav Petkov <petkovbb@gmail.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

drivers/ide/ide-taskfile.c

@@ -100,13 +100,14 @@ ide_startstop_t do_rw_taskfile(ide_drive_t *drive, struct ide_cmd *orig_cmd)
 		ide_execute_command(drive, tf->command, handler,
 				    WAIT_WORSTCASE, NULL);
 		return ide_started;
-	default:
+	case ATA_PROT_DMA:
 		if ((drive->dev_flags & IDE_DFLAG_USING_DMA) == 0 ||
 		    ide_build_sglist(drive, cmd) == 0 ||
 		    dma_ops->dma_setup(drive, cmd))
 			return ide_stopped;
 		dma_ops->dma_exec_cmd(drive, tf->command);
 		dma_ops->dma_start(drive);
+	default:
 		return ide_started;
 	}
 }