dt-bindings: phy: ti,tcan104x-can: Document mux-states property

On some boards, for routing CAN signals from controller to transceivers,
muxes might need to be set. This can be implemented using mux-states
property. Therefore, document the same in the respective bindings.

Signed-off-by: Aswath Govindraju <a-govindraju@ti.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20211216041012.16892-2-a-govindraju@ti.com