dt-bindings: phy-qcom: Add support for msm8998 usb

USB on msm8998 utilizes the QUSB2 and QMP phys, similar to sdm845.

Signed-off-by: Jeffrey Hugo <jhugo@codeaurora.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>