arm: dts: add cooling properties on omap4460 cpu node

OMAP4460 devices can reach high temperatures and thus
needs to have cpufreq-cooling on systems running on it.

This patch adds the required cooling device properties
so that cpufreq-cpu0 driver loads the cooling device.

Cc: "Benoît Cousson" <bcousson@baylibre.com>
Cc: Tony Lindgren <tony@atomide.com>
Cc: Rob Herring <rob.herring@calxeda.com>
Cc: Pawel Moll <pawel.moll@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Stephen Warren <swarren@wwwdotorg.org>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: linux-omap@vger.kernel.org
Cc: devicetree@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Eduardo Valentin <eduardo.valentin@ti.com>