usb: dwc3: core: don't kfree() devm_kzalloc()'ed memory

commit 380f0d28 (usb: dwc3: core: switch event
buffer allocation to devm_kzalloc()) was incomplete
leaving a trailing kfree(evt) in an error exit
path.

Fix this problem by removing the trailing kfree(evt).

Cc: Julia Lawall <julia.lawall@lip6.fr>
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/dwc3/core.c

@@ -153,10 +153,8 @@ dwc3_alloc_one_event_buffer(struct dwc3 *dwc, unsigned length)
 	evt->length	= length;
 	evt->buf	= dma_alloc_coherent(dwc->dev, length,
 			&evt->dma, GFP_KERNEL);
-	if (!evt->buf) {
-		kfree(evt);
+	if (!evt->buf)
 		return ERR_PTR(-ENOMEM);
-	}
 
 	return evt;
 }