ARM: dts: Fix omap serial wake-up when booted with device tree

We've had deeper idle states working on omaps for few years now,
but only in the legacy mode. When booted with device tree, the
wake-up events did not have a chance to work until commit
3e6cee17 (pinctrl: single: Add support for wake-up interrupts)
that recently got merged. In addition to that we also needed commit
79d97015 (of/irq: create interrupts-extended property) and
9ec36caf (of/irq: do irq resolution in platform_get_irq) that
are now also merged.

So let's fix the wake-up events for some selected omaps so devices
booted in device tree mode won't just hang if deeper power states
are enabled, and so systems can wake up from suspend to the serial
port event.

Note that there's no longer need to specify the wake-up bit in
the pinctrl settings, the request_irq on the wake-up pin takes
care of that.

Cc: devicetree@vger.kernel.org
Cc: "Benoît Cousson" <bcousson@baylibre.com>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Nishanth Menon <nm@ti.com>
Cc: Paul Walmsley <paul@pwsan.com>
Cc: Tero Kristo <t-kristo@ti.com>
[tony@atomide.com: updated comments, added board LDP]
Signed-off-by: Tony Lindgren <tony@atomide.com>