igc: Fix the parameter description for igc_alloc_rx_buffers

The function description for igc_alloc_rx_buffers has not reflected
the function meaning. Add meaningful description.
Signed-off-by: Sasha Neftin <sasha.neftin@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/igc/igc_main.c

@@ -1566,7 +1566,8 @@ static void igc_put_rx_buffer(struct igc_ring *rx_ring,
 
 /**
  * igc_alloc_rx_buffers - Replace used receive buffers; packet split
- * @adapter: address of board private structure
+ * @rx_ring: rx descriptor ring
+ * @cleaned_count: number of buffers to clean
  */
 static void igc_alloc_rx_buffers(struct igc_ring *rx_ring, u16 cleaned_count)
 {