staging: fsl-dpaa2/eth: Use implicit clear of link interrupt

dpni_get_irq_status() also looks at the input value of its
status parameter, and if not null it automatically clears
from pending state the bits that are set there.

Use this feature to avoid a separate MC command for clearing
the interrupt event bits after reading the status.

Signed-off-by: Ioana Radulescu <ruxandra.radulescu@nxp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>