usb: dwc2: move "samsung,s3c6400-hsotg" into common platform

Move the "samsung,s3c6400-hsotg" binding as the probe function in the gadget
driver will get removed when the dual-role driver is implemented.

Signed-off-by: Dinh Nguyen <dinguyen@opensource.altera.com>
Acked-by: Paul Zimmerman <paulz@synopsys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>