staging: r8188eu: change return type of rtw_set_802_11_disassociate to void

staging: r8188eu: change return type of rtw_set_802_11_disassociate to void

Change return type of rtw_set_802_11_disassociate to void. This function
always returns 'true' no matter what, so there is no need to return a
value, and no need to check for it in the two call sites within
rtw_wx_set_mlme. Also, as we are no longer using ret in rtw_wx_set_mlme
except as the return value, just remove it and return 0 directly.

Suggested-by: Michael Straube <straube.linux@gmail.com>
Signed-off-by: Phillip Potter <phil@philpotter.co.uk>
Tested-by: Philipp Hortmann <philipp.g.hortmann@gmail.com> # Edimax N150
Link: https://lore.kernel.org/r/20221103230632.6946-1-phil@philpotter.co.uk
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>