usb: Kconfig: config USB_XHCI_ROCKCHIP depends on DM_REGULATOR and DM_USB

The xhci-rockchip driver depends on DM_REGULATOR and DM_USB.
So add dependent features for xhci-rockchip driver in Kconfig.

Signed-off-by: Meng Dongyang <daniel.meng@rock-chips.com>
Reviewed-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Acked-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>