arm64: dts: ti: k3-j721s2-main: Add C7x remote processsor nodes

arm64: dts: ti: k3-j721s2-main: Add C7x remote processsor nodes

The K3 J721S2 SoCs have two C71x DSP subsystems in MAIN voltage domain. The
C71x DSPs are 64 bit machine with fixed and floating point DSP operations.
Similar to the R5F remote cores, the inter-processor communication
between the main A72 cores and these DSP cores is achieved through
shared memory and Mailboxes.

The following firmware names are used by default for these DSP cores,
and can be overridden in a board dts file if desired:
        MAIN C71_0 : j721s2-c71_0-fw
        MAIN C71_1 : j721s2-c71_1-fw

Signed-off-by: Hari Nagalla <hnagalla@ti.com>
Signed-off-by: Apurva Nandan <a-nandan@ti.com>
Reviewed-by: Andrew Davis <afd@ti.com>
Link: https://lore.kernel.org/r/20231001181417.743306-4-a-nandan@ti.com
Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>