irqchip/irq-bcm7038-l1: Enable parent IRQ if necessary

If the 'brcm,irq-can-wake' property is specified, make sure we also
enable the corresponding parent interrupt we are attached to.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20191024201415.23454-4-f.fainelli@gmail.com