odroid-c2: enable USB host controller

Enable the second USB controller, which is connected to a hub with 4
ports. The first controller is for the OTG port and is currently not
supported.

Signed-off-by: Beniamino Galvani <b.galvani@gmail.com>
[narmstrong: removed useless DWC2_UTMI_WIDTH in meson64.h]
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>