ide-disk: fix missing max_sectors accessor function

The recent move to accessor functions for querying queue limits
missed an entry in ide-disk.c:

drivers/ide/ide-disk.c: In function ‘ide_disk_setup’:
drivers/ide/ide-disk.c:642: error: ‘struct request_queue’ has no member named ‘max_sectors’

Fix it.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>