The ret variable may not be initialized in rk_udphy_usb3_phy_init(), if
the PHY is not using USB3 mode.

Since the DisplayPort part is handled separately and the PHY does not
support USB2 (which is routed to another PHY on Rockchip RK3588), the
right exit code for this case is 0. Thus let's initialize the variable
accordingly.

Fixes: 2f70bbdd ("phy: rockchip: add usbdp combo phy driver")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202404141048.qFAYDctQ-lkp@intel.com/Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Reviewed-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Link: https://lore.kernel.org/r/20240416145233.94687-1-sebastian.reichel@collabora.comSigned-off-by: Vinod Koul <vkoul@kernel.org>