arm64: dts: exynos: use local header for pinctrl register values

The DTS uses hardware register values directly in pin controller pin
configuration.  These are not some IDs or other abstraction layer but
raw numbers used in the registers.

These numbers were previously put in the bindings header to avoid code
duplication and to provide some context meaning (name), but they do not
fit the purpose of bindings.

Store the constants in a header next to DTS and use them instead of
bindings.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Chanho Park <chanho61.park@samsung.com>
Tested-by: Chanho Park <chanho61.park@samsung.com>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220605160508.134075-6-krzysztof.kozlowski@linaro.org