ARM: davinci: cp_intc: use IRQCHIP_SKIP_SET_WAKE instead of irq_set_wake callback

Commit 60f96b41 ("genirq: Add IRQCHIP_SKIP_SET_WAKE flag")
introduced a new flag to skip the irq_set_wake callback in the irqchip
core to avoid adding dummy irq_set_wake in the irqchip implementations.

This patch removes the dummy callback and sets the IRQCHIP_SKIP_SET_WAKE
flags.

Cc: Sekhar Nori <nsekhar@ti.com>
Cc: Kevin Hilman <khilman@deeprootsystems.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>
Signed-off-by: Olof Johansson <olof@lixom.net>