usb: gadget zero: avoid unnecessary reinit of data in f_sourcesink

In the IN case, since the USB request is allocated only when
the source/sink function is started and never freed, the USB ept
buffer needs to be initialized only at the beginning. This change
results into a more performant g_zero module, especially when
'pattern=1' is selected.
Signed-off-by: Armando Visconti <armando.visconti@st.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/gadget/f_sourcesink.c

@@ -531,8 +531,7 @@ static void source_sink_complete(struct usb_ep *ep, struct usb_request *req)
 			check_read_data(ss, req);
 			if (pattern != 2)
 				memset(req->buf, 0x55, req->length);
-		} else
-			reinit_write_data(ep, req);
+		}
 		break;
 
 	/* this endpoint is normally active while we're configured */