usb: dwc3: gadget: Clear delayed_status on reset

If the host issued BUS RESET just after the SETUP packet
for which the composite device has sent the DELAYED_STATUS,
the device does not respond on the next SETUP which is
generally GET_DEVICE_DESCRIPTOR.
Fix this by clearing the delayed_status on BUS RESET to
ensure the response from composite device for
GET_DEVICE_DESCRIPTOR can be queued properly on endpoint 0.

Change-Id: I5e93b5e3c61eb943443a4ef9ec554de2935dfb4e
Signed-off-by: Sriharsha Allenki <sallenki@codeaurora.org>