dt-bindings: pinctrl: samsung: drop unused header with register constants

The bindings header for Samsung pin controller DTS pin values (holding
register values in fact) was deprecated in v6.1 kernel in
commit 9d929257 ("dt-bindings: pinctrl: samsung: deprecate header
with register constants").  This was enough of time for users to switch
to in-DTS headers, so drop the bindings header.

Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20240312164428.692552-1-krzysztof.kozlowski@linaro.org


Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>