[PATCH] hostap: Suppress broadcast if no stations are associated

This may be useful in mesh setups when most stations act as repeaters only.

Signed-off-by: Pavel Roskin <proski@gnu.org>
Signed-off-by: Jouni Malinen <j@w1.fi>
Signed-off-by: John W. Linville <linville@tuxdriver.com>