usb: dwc3: core: switch event buffer allocation to devm_kzalloc()

The rest of the driver is using devm_kzalloc() where possible
and this patch is just making event buffer allocation follow
the example.
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/dwc3/core.c

@@ -169,7 +169,6 @@ static void dwc3_free_one_event_buffer(struct dwc3 *dwc,
 		struct dwc3_event_buffer *evt)
 {
 	dma_free_coherent(dwc->dev, evt->length, evt->buf, evt->dma);
-	kfree(evt);
 }
 
 /**
@@ -185,7 +184,7 @@ dwc3_alloc_one_event_buffer(struct dwc3 *dwc, unsigned length)
 {
 	struct dwc3_event_buffer	*evt;
 
-	evt = kzalloc(sizeof(*evt), GFP_KERNEL);
+	evt = devm_kzalloc(dwc->dev, sizeof(*evt), GFP_KERNEL);
 	if (!evt)
 		return ERR_PTR(-ENOMEM);
 
@@ -215,8 +214,6 @@ static void dwc3_free_event_buffers(struct dwc3 *dwc)
 		if (evt)
 			dwc3_free_one_event_buffer(dwc, evt);
 	}
-
-	kfree(dwc->ev_buffs);
 }
 
 /**
@@ -235,7 +232,8 @@ static int __devinit dwc3_alloc_event_buffers(struct dwc3 *dwc, unsigned length)
 	num = DWC3_NUM_INT(dwc->hwparams.hwparams1);
 	dwc->num_event_buffers = num;
 
-	dwc->ev_buffs = kzalloc(sizeof(*dwc->ev_buffs) * num, GFP_KERNEL);
+	dwc->ev_buffs = devm_kzalloc(dwc->dev, sizeof(*dwc->ev_buffs) * num,
+			GFP_KERNEL);
 	if (!dwc->ev_buffs) {
 		dev_err(dwc->dev, "can't allocate event buffers array\n");
 		return -ENOMEM;