UPSTREAM: usb: dwc2: Move mode querying functions into core.h

UPSTREAM: usb: dwc2: Move mode querying functions into core.h

These functions should go in core.h where they can be called from core,
device, or host.

Change-Id: I03e22ee0f6819998d152fab25c5b0b47e76275e1
Signed-off-by: John Youn <johnyoun@synopsys.com>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Tested-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 1696d5ab99ef885ae62da5ad58f9eff16da7ff78)