usb: dwc2: host: fix the data toggle error in full speed descriptor dma

There will be data toggle error happen for full speed buld-out transfer.
The data toggle bit is saved in qh for non-control transfers, it is wrong
to  check the qtd for that case.

Also fix one static analysis tool issue after fix the data toggle error.

John Youn:
* Added WARN() to warn on improper usage of the
  dwc2_hcd_save_data_toggle() function.

Signed-off-by: Dyson Lee <dyson.lee@intel.com>
Signed-off-by: Tang, Jianqiang <jianqiang.tang@intel.com>
Signed-off-by: John Youn <johnyoun@synopsys.com>
Signed-off-by: Felipe Balbi <balbi@kernel.org>