dt-bindings: phy: Add binding for qcom,usb-snps-femto-v2

This binding shows the descriptions and properties for the
Synopsis Femto USB PHY V2 used on QCOM platforms.

Signed-off-by: Wesley Cheng <wcheng@codeaurora.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Stephen Boyd <sboyd@kernel.org>
Link: https://lore.kernel.org/r/1588636467-23409-2-git-send-email-wcheng@codeaurora.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>