w1: omap_hdq: use wait_event_timeout to wait for read to complete.

There is no gain in having a loop - there is no risk of missing the
interrupt with wait_event_timeout.

Signed-off-by: NeilBrown <neilb@suse.de>
Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>