usb: renesas_usbhs: set quirk_avoids_skb_reserve if USB-DMAC is used

This patch sets the quirk_avoids_skb_reserve flag to improve performance
of a network gadget driver (e.g. f_ncm.c) if USB-DMAC is used.

For example (on r8a7795 board + f_ncm.c + iperf udp mode / receiving):
  - without this patch:  90.3 Mbits/sec
  - with    this patch: 273   Mbits/sec
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

drivers/usb/renesas_usbhs/mod_gadget.c

@@ -1102,6 +1102,8 @@ int usbhs_mod_gadget_probe(struct usbhs_priv *priv)
 	gpriv->gadget.name		= "renesas_usbhs_udc";
 	gpriv->gadget.ops		= &usbhsg_gadget_ops;
 	gpriv->gadget.max_speed		= USB_SPEED_HIGH;
+	gpriv->gadget.quirk_avoids_skb_reserve = usbhs_get_dparam(priv,
+								has_usb_dmac);
 
 	INIT_LIST_HEAD(&gpriv->gadget.ep_list);