staging; rtl8723bs: Remove unnecessary function rtw_init_mlme_priv()

Remove function rtw_init_mlme_priv() as all it does is call
_rtw_init_mlme_priv().
Change the name of _rtw_init_mlme_priv() to rtw_init_mlme_priv() and its
return type to int.
Remove references to _rtw_init_mlme_priv() from the corresponding header
file.
Suggestion to delete return variable from rtw_init_mlme_priv() put forward
by Coccinelle using ret.cocci.

Signed-off-by: Nishka Dasgupta <nishka.dasgupta@yahoo.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>