dt-bindings: pinctrl: qcom,sdx65-tlmm: add pcie_clkreq function

dt-bindings: pinctrl: qcom,sdx65-tlmm: add pcie_clkreq function

DTS and driver already support pcie_clkreq function for a pin.  Add it
to fix dtbs_check warning:

  qcom-sdx65-mtp.dtb: pinctrl@f100000: pcie-ep-clkreq-default-state: 'oneOf' conditional failed, one must be fixed:
    'bias-disable', 'drive-strength', 'function', 'pins' do not match any of the regexes: '-pins$', 'pinctrl-[0-9]+'
    'pcie_clkreq' is not one of ['blsp_uart1', 'blsp_spi1', ... 'gpio']

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230617111809.129232-1-krzysztof.kozlowski@linaro.org
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>