Revert "usb: renesas_usbhs: add extcon notifier to set mode for non-otg channel"

This reverts commit 8ada211d.

R-Car D3 can use OTG mode in fact. So, the commit doesn't need anymore.
In other words, like other R-Car Gen3 SoCs, R-Car D3 can change the mode
by using the phy-rcar-gen3-usb2 driver.

Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>