rockchip: xhci: remove DTS parsing for PHY (which is unused)
The xhci wrapper-driver for Rockchip searches the DTS to find its
child node compatbile with 'rockchip,rk3399-usb3-phy' to retrieve the
base-address of the PHY. However, this is currently broken (and
always has been), returning NULL. However, the (wrongly) retrieved
base-address is never used.
We thus remove this code for now.
Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>