dt-bindings: soc: qcom: Introduce PMIC GLINK binding

The PMIC GLINK service, running on a coprocessor on some modern Qualcomm
platforms and implement USB Type-C handling and battery management.
This binding describes the component in the OS used to communicate with
the firmware and connect it's resources to those described in the
Devicetree, particularly the USB Type-C controllers relationship with
USB and DisplayPort components.

Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>