dt-bindings: soc: ti: pruss: Update bindings for K3 AM64x SoCs

The K3 AM64x SoCs also have the Gigabit Ethernet capable PRU-ICSS IP
that is present on existing K3 AM65x and J721E SoCs (ICSSG). The IP
is similar to the ones used on K3 J721E or AM65x SR2.0 SoCs.

Update the PRUSS bindings for these ICSSG instances.

Signed-off-by: Suman Anna <s-anna@ti.com>
Reviewed-by: Grygorii Strashko <grygorii.strashko@ti.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>