i40e: add function header for i40e_get_rxfh

Someone left this poor little function naked with no header.  This
dresses it up in a proper function header it deserves.

Signed-off-by: Alan Brady <alan.brady@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_ethtool.c

@@ -3968,6 +3968,16 @@ static u32 i40e_get_rxfh_indir_size(struct net_device *netdev)
 	return I40E_HLUT_ARRAY_SIZE;
 }
 
+/**
+ * i40e_get_rxfh - get the rx flow hash indirection table
+ * @netdev: network interface device structure
+ * @indir: indirection table
+ * @key: hash key
+ * @hfunc: hash function
+ *
+ * Reads the indirection table directly from the hardware. Returns 0 on
+ * success.
+ **/
 static int i40e_get_rxfh(struct net_device *netdev, u32 *indir, u8 *key,
 			 u8 *hfunc)
 {