dt-bindings: pinctrl: qcom: Add SDX65 pinctrl bindings

Add device tree binding Documentation details for Qualcomm SDX65
pinctrl driver.

Signed-off-by: Vamsi Krishna Lanka <quic_vamslank@quicinc.com>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/ff9abf953c274a1e34f59114642f67ecf02acb6f.1639696427.git.quic_vamslank@quicinc.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>