staging: rtl8188eu: Remove unused functons defined in rtw_br_ext.c

This patch removes some functions defined in rtw_br_ext.c, which have become
obsolete after removal of rtw_br_client_tx().

Signed-off-by: navin patidar <navin.patidar@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>