net-next: ax88796: set IRQF_SHARED flag when IRQ resource is marked as shareable

On the Amiga X-Surf100, the network card interrupt is shared with many
other interrupt sources, so requires the IRQF_SHARED flag to register.

Signed-off-by: Michael Karcher <kernel@mkarcher.dialup.fu-berlin.de>
Signed-off-by: Michael Schmitz <schmitzmic@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>