drivers: udc_dwc2: Disable control IN endpoint on timeout

DWC2 core sets DIEPCTL0 SNAK when SETUP packet is received. The CNAK bit
results in device sending NAK in response to IN token sent to EP0, but
it does not modify the TxFIFO in any way. The stale data in TxFIFO can
then lead to "FIFO space is too low" error. Solve the issue by disabling
and flushing IN endpoint 0 if previous control transfer did not finish.

Signed-off-by: Tomasz Moń <tomasz.mon@nordicsemi.no>