dt-bindings: pinctrl: qcom: Add SDM660 pinctrl binding

Add the binding for the TLMM pinctrl block found in the SDM660 platform.

Signed-off-by: Craig Tatlor <ctatlor97@gmail.com>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>