staging: r8188eu: make on_action_public static void

staging: r8188eu: make on_action_public static void

The on_action_public function is called only by OnAction. This function
also lives in rtw_mlme_ext.c and does not check the return value from
on_action_public.

We can make on_action_public a static void function.

The ret variable is no longer needed if we don't return a value. It can
be removed.

Reported-by: kernel test robot <lkp@intel.com>
Tested-by: Philipp Hortmann <philipp.g.hortmann@gmail.com> # Edimax N150
Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Link: https://lore.kernel.org/r/20221030173326.1588647-4-martin@kaiser.cx
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>