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>
diff --git a/README b/README
index 19abe20..d9a64ea 100644
--- a/README
+++ b/README
@@ -1465,6 +1465,9 @@
 		CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
 		txfilltuning field in the EHCI controller on reset.
 
+		CONFIG_USB_DWC2_REG_ADDR the physical CPU address of the DWC2
+		HW module registers.
+
 - USB Device:
 		Define the below if you wish to use the USB console.
 		Once firmware is rebuilt from a serial console issue the