i40e: fix for queue timing delays

This patch adds a delay to Rx queue disables to accommodate HW needs.

v2: Added missing check for disable only, additional details on the
need for the ugly delay and fixed spacing on comment.

Change-ID: I2864ca667ce5dcc2cc44f8718113b719742a46a1
Signed-off-by: Carolyn Wyborny <carolyn.wyborny@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/i40e/i40e_main.c

@@ -4067,6 +4067,12 @@ static int i40e_vsi_control_rx(struct i40e_vsi *vsi, bool enable)
 		}
 	}
 
+	/* Due to HW errata, on Rx disable only, the register can indicate done
+	 * before it really is. Needs 50ms to be sure
+	 */
+	if (!enable)
+		mdelay(50);
+
 	return ret;
 }