usb: dwc3: gadget: return error if command sent to DGCMD register fails

We need to return error to caller if command is not sent to
controller succesfully.

Signed-off-by: Subbaraya Sundeep Bhatta <sbhatta@xilinx.com>
Fixes: b09bb64239c8 (usb: dwc3: gadget: implement Global Command support)
Cc: <stable@vger.kernel.org> #v3.5+
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/dwc3/gadget.c

@@ -291,6 +291,8 @@ int dwc3_send_gadget_generic_command(struct dwc3 *dwc, unsigned cmd, u32 param)
 			dwc3_trace(trace_dwc3_gadget,
 					"Command Complete --> %d",
 					DWC3_DGCMD_STATUS(reg));
+			if (DWC3_DGCMD_STATUS(reg))
+				return -EINVAL;
 			return 0;
 		}