dt-bindings: phy: Convert ti,keystone-usbphy to DT schema

Convert the TI Keystone USB PHY binding to DT schema format. Drop the
"#address-cells" and "#size-cells" properties which don't make sense
without any child nodes.

Signed-off-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://lore.kernel.org/r/20250607212641.744683-1-robh@kernel.org


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