dt-bindings: timer: new bindings for TI DaVinci timer

This adds new device tree bindings for the timer IP block of TI
DaVinci-like SoCs.

Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: David Lechner <david@lechnology.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>