dt-bindings: net: Add support for AM65x SR1.0 in ICSSG

Silicon Revision 1.0 of the AM65x came with a slightly different ICSSG
support: Only 2 PRUs per slice are available and instead 2 additional
DMA channels are used for management purposes. We have no restrictions
on specified PRUs, but the DMA channels need to be adjusted.

Co-developed-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Diogo Ivo <diogo.ivo@siemens.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Roger Quadros <rogerq@kernel.org>
Reviewed-by: MD Danish Anwar <danishanwar@ti.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>