ide: add ide_execute_pkt_cmd() helper

Add ide_execute_pkt_cmd() helper for executing PACKET command,
then convert ATAPI device drivers to use it.

As a nice side-effect this fixes ide-{floppy,tape,scsi} w.r.t.
ide_lock taking (ide-cd was OK).

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

drivers/ide/ide-floppy.c

@@ -696,9 +696,7 @@ static ide_startstop_t idefloppy_issue_pc(ide_drive_t *drive,
 		return ide_started;
 	} else {
 		/* Issue the packet command */
-		hwif->OUTBSYNC(drive, WIN_PACKETCMD,
-			       hwif->io_ports.command_addr);
-		ndelay(400);
+		ide_execute_pkt_cmd(drive);
 		return (*pkt_xfer_routine) (drive);
 	}
 }