usb: dwc3-uniphier: Use dwc3-generic instead of xhci-dwc3

dwc3-uniphier depends on xhci-dwc3 framework, however, it is preferable
to use dwc3-generic.

This driver calls the exported dwc3-generic functions and redefine
the SoC-dependent operations to fit dwc3-generic.

Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
Reviewed-by: Marek Vasut <marex@denx.de>