The DTS uses constants for SERDES MUX idle state values which were earlier
provided as bindings header. But they are unsuitable for bindings.
So move these constants in a header next to DTS.

Also add J784S4 SERDES4 lane definitions which were missed earlier.
Suggested-by: Nishanth Menon <nm@ti.com>
Suggested-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Suggested-by: Roger Quadros <rogerq@kernel.org>
Link: https://lore.kernel.org/linux-arm-kernel/b24c2124-fe3b-246c-9af9-3ecee9fb32d4@kernel.org/Signed-off-by: Jayesh Choudhary <j-choudhary@ti.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Acked-by: Roger Quadros <rogerq@kernel.org>
Acked-by: Peter Rosin <peda@axentia.se>
Link: https://lore.kernel.org/r/20230721125732.122421-2-j-choudhary@ti.comSigned-off-by: Nishanth Menon <nm@ti.com>