usb: dwc3: gadget: Fix usage of bitwise operator

Cleans up the sparse warning:
warning: dubious: x | !y

Since we do want a bitwise OR here, don't use a logical (true/false)
value. Probably is not a real issue but it cleans up the warning.

Signed-off-by: John Youn <johnyoun@synopsys.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>