UPSTREAM: usb: dwc2: Add functions to check the HW OTG config

UPSTREAM: usb: dwc2: Add functions to check the HW OTG config

Added functions to query the GHWCFG2.OTG_MODE. This tells us whether the
controller hardware is configured for OTG, device-only, or host-only.

Change-Id: I8f927d130a675ceb598b118d0c9a4e5d5b698739
Signed-off-by: John Youn <johnyoun@synopsys.com>
Tested-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Huang, Tao <huangtao@rock-chips.com>
(cherry picked from commit 6bea962053e76a4407f0d138184a8737eea960ee)