dt-bindings: pinctrl: k3: Deprecate header with register constants

dt-bindings: pinctrl: k3: Deprecate header with register constants

For convenience (less code duplication), the pin controller pin
configuration register values were defined in the bindings header.
These are not some IDs or other abstraction layer but raw numbers used
in the registers.

These constants do not fit the purpose of bindings. They do not
provide any abstraction, any hardware and driver independent ID. In
fact, the Linux pinctrl-single driver actually do not use the bindings
header at all.

All of the constants were moved already to headers local to DTS
(residing in DTS directory), so remove any references to the bindings
header and add a warning that it is deprecated.

Suggested-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/linux-arm-kernel/71c7feff-4189-f12f-7353-bce41a61119d@linaro.org/
Link: https://lore.kernel.org/r/20230315155228.1566883-4-nm@ti.com
Signed-off-by: Nishanth Menon <nm@ti.com>