dt-bindings: phy: remove qcom-dwc3-usb-phy

This binding is not used by any driver.

Signed-off-by: Jorge Ramirez-Ortiz <jorge.ramirez-ortiz@linaro.org>
Cc: Jorge Ramirez-Ortiz <jorge.ramirez.ortiz@gmail.com>
Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>