staging: rtl8192u: remove the repeated declaration

Functions 'ieee80211_stop_send_beacons' and 'notify_wx_assoc_event'
are declared twice in their header file, so remove the repeated
declaration.

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Shaokun Zhang <zhangshaokun@hisilicon.com>
Link: https://lore.kernel.org/r/1622446678-52652-1-git-send-email-zhangshaokun@hisilicon.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>