sh: intc: enable both edges GPIO interrupts on sh7372

IRQ-capable GPIOs on sh7372 can be configured to produce interrupts on
both edges.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Acked-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>