dt-bindings: net: ti: Update maintainers list

Update the list with the current maintainers of TI's CPSW ethernet
peripheral.

Signed-off-by: Ravi Gunasekaran <r-gunasekaran@ti.com>
Acked-by: Roger Quadros <rogerq@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>