usb: dwc3: Track DWC_usb31 VERSIONTYPE

Add a new field to dwc3 structure to track VERSIONTYPE. The VERSIONTYPE
is represented in ASCII in the 32-bit VERSIONTYPE register. In
DWC_usb31, sub releases for each version are tracked with VERSIONTYPE
such as "ea01" and "ea02".

Signed-off-by: Thinh Nguyen <thinhn@synopsys.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>