Certain pins, like SDcard related, do not have functions and such should
not be required:

  sdc1-clk-pins: 'function' is a required property
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20220912061746.6311-9-krzysztof.kozlowski@linaro.orgSigned-off-by: Linus Walleij <linus.walleij@linaro.org>