dt-bindings: ti-serdes-mux: Add defines for J721S2 SoC

There are 4 lanes in the single instance of J721S2 SERDES. Each SERDES
lane mux can select upto 4 different IPs. Define all the possible
functions.

Signed-off-by: Aswath Govindraju <a-govindraju@ti.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Peter Rosin <peda@axentia.se>
Link: https://lore.kernel.org/r/0571fd6b-ec4d-71b3-5cf7-6fa48ed5592c@axentia.se


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>