dt-bindings: phy: qcom,qusb2: Document msm8953 compatible

Document the compatible string used for the qusb2 phy in msm8953.

Signed-off-by: Luca Weiss <luca@z3ntu.xyz>
Acked-by: Konrad Dybcio <konrad.dybcio@somainline.org>
Link: https://lore.kernel.org/r/20220112194118.178026-2-luca@z3ntu.xyz


Signed-off-by: Vinod Koul <vkoul@kernel.org>