usb: dwc2: Pass private data into dwc_otg_core_init()

Pass the whole bulk of private data instead of just the regs,
since the private data will soon contain important configuration
flags.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Stefan Roese <sr@denx.de>
Cc: Dinh Nguyen <dinguyen@kernel.org>