[ARM] pxa/colibri: get rid of set_irq_type()

In commit 47cb0355, the ax88796 driver
learned to take IRQ flags from platform_device definition. Use that here
to get rid of the set_irq_type() hack.

Signed-off-by: Daniel Mack <daniel@caiaq.de>
Signed-off-by: Eric Miao <eric.miao@marvell.com>