staging: rtl8188eu: core: Replace function rtw_free_network_nolock()

Remove function rtw_free_network_nolock, as all it does is call
_rtw_free_network_nolock, and rename _rtw_free_network_nolock to
rtw_free_network_nolock.
Keep the new rtw_free_network_nolock a static function and remove the
old version from the header file.

Signed-off-by: Nishka Dasgupta <nishkadg.linux@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>