dt-bindings: remoteproc: Add bindings for DSP C66x clusters on TI K3 SoCs

dt-bindings: remoteproc: Add bindings for DSP C66x clusters on TI K3 SoCs

Some Texas Instruments K3 family of SoCs have one of more Digital Signal
Processor (DSP) subsystems that are comprised of either a TMS320C66x
CorePac and/or a next-generation TMS320C71x CorePac processor subsystem.
Add the device tree bindings document for the C66x DSP devices on these
SoCs. The added example illustrates the DT nodes for the first C66x DSP
device present on the K3 J721E family of SoCs.

Signed-off-by: Suman Anna <s-anna@ti.com>
Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>