w1: ds1wm: silence interrupts on HW before claiming the interrupt

w1: ds1wm: silence interrupts on HW before claiming the interrupt.
This way avoid possible invalid interrupts in the initialization phase.

Signed-off-by: Johannes Poehlmann <johannes.poehlmann@izt-labs.de>
Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>