usb: dwc2: Add driver for Synopsis DWC2 USB IP block

This is the USB host controller used on the Altera SoCFPGA and Raspbery Pi.

This code has three checkpatch warnings, but to make sure it stays at least
readable and clear, these are not fixed. These bugs are in the USB request
handling combinatorial logic, so any abstracting of those is out of question.

Tested on DENX MCV (Altera SoCFPGA 5CSFXC6C6U23C8N) and RPi B+ (BCM2835).

Signed-off-by: Oleksandr Tymoshenko <gonzo@bluezbox.com>
Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Chin Liang See <clsee@altera.com>
Cc: Dinh Nguyen <dinguyen@altera.com>
Acked-by: Pavel Machek <pavel@denx.de>
Cc: Vince Bridgers <vbridger@altera.com>
Tested-by: Dinh Nguyen <dinguyen@opensource.altera.com>