dt-bindings: remoteproc: Add bindings for R5F subsystem on TI K3 SoCs

dt-bindings: remoteproc: Add bindings for R5F subsystem on TI K3 SoCs

The Texas Instruments K3 family of SoCs have one of more dual-core
Arm Cortex R5F processor subsystems/clusters (R5FSS). Add the device
tree bindings document for these R5F subsystem devices. These R5F
processors do not have an MMU, and so require fixed memory carveout
regions matching the firmware image addresses. The nodes require more
than one memory region, with the first memory region used for DMA
allocations at runtime. The remaining memory regions are reserved
and are used for the loading and running of the R5F remote processors.

The added example illustrates the DT nodes for the single R5FSS device
present on K3 AM65x family of SoCs.

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