i40e: add doxygen comment for new mode parameter

A recent patch updated the signature for i40e_aq_set_switch_config() to
add a new parameter 'mode'. It forgot to document the parameter in the
doxygen function header comment. Add the parameter to the function
description now.
Signed-off-by: Jacob Keller <jacob.e.keller@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_common.c

@@ -2415,6 +2415,7 @@ i40e_status i40e_aq_get_switch_config(struct i40e_hw *hw,
  * i40e_aq_set_switch_config
  * @hw: pointer to the hardware structure
  * @flags: bit flag values to set
+ * @mode: cloud filter mode
  * @valid_flags: which bit flags to set
  * @mode: cloud filter mode
  * @cmd_details: pointer to command details structure or NULL