dpaa2-switch: do not clear any interrupts automatically

The DPSW object has multiple event sources multiplexed over the same
IRQ. The driver has the capability to configure only some of these
events to trigger the IRQ.

The dpsw_get_irq_status() can clear events automatically based on the
value stored in the 'status' variable passed to it. We don't want that
to happen because we could get into a situation when we are clearing
more events than we actually handled.

Just resort to manually clearing the events that we handled. Also, since
status is not used on the out path we remove its initialization to zero.

This change does not have a user-visible effect because the dpaa2-switch
driver enables and handles all the DPSW events which exist at the
moment.

Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>