usb: dwc3: Add generic DWC3 glue logic driver

By enabling BLK by default this is the next driver which needs to get
support for DM_USB. Adding generic DWC3 glue logic which only
parse nodes and read device mode. Based on it probe proper
host/peripheral DWC3 drivers for it.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>