arm64: dts: ti: k3-j7200-main: Add SERDES lane control mux

The SERDES lane control mux registers are present in the
CTRLMMR space.

Signed-off-by: Roger Quadros <rogerq@ti.com>
Signed-off-by: Nishanth Menon <nm@ti.com>
Reviewed-by: Vignesh Raghavendra <vigneshr@ti.com>
Link: https://lore.kernel.org/r/20200930122032.23481-3-rogerq@ti.com