ARM: LPC32xx: Use handle_edge_irq() callback on edge type irqs

irq.c uses handle_level_irq() as the unconditional default handler. This patch
uses handle_edge_irq() instead for edge type irqs.

Signed-off-by: Roland Stigge <stigge@antcom.de>
Acked-by: Srinivas Bakki <srinivas.bakki@nxp.com>