usb: dwc2: gadget: use | instead of + for bitmasks

It's just a lot clearer to use | operator instead of
+ operator.

Caught by coccicheck:

	"
	drivers/usb/dwc2/gadget.c:2883:26-27: WARNING: sum of probable
	bitmasks, consider |
	"

Cc: John Youn <John.Youn@synopsys.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/dwc2/gadget.c

@@ -2880,7 +2880,7 @@ static int s3c_hsotg_ep_sethalt(struct usb_ep *ep, int value)
 		epctl = readl(hs->regs + epreg);
 
 		if (value) {
-			epctl |= DXEPCTL_STALL + DXEPCTL_SNAK;
+			epctl |= DXEPCTL_STALL | DXEPCTL_SNAK;
 			if (epctl & DXEPCTL_EPENA)
 				epctl |= DXEPCTL_EPDIS;
 		} else {