ide: move ide_port_setup_devices() call to ide_device_add_all()

Add ide_cfg_mtx lock/unlock to ide_port_setup_devices() and then move
ide_port_setup_devices() call from init_irq() to ide_device_add_all().

Acked-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>