staging:r8188eu: remove unused struct wifidirect_info and all corresponding code

wifidirect_info structure is unused.
Big amount of another definitions used only for wifidirect_info definition.
Remove all.

Signed-off-by: Ivan Safonov <insafonov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>