r92su: support devices with 6 and 11 endpoints

Signed-off-by: Christian Lamparter <chunkeey@googlemail.com>
r92su: disable ht if device does not support it

Signed-off-by: Christian Lamparter <chunkeey@googlemail.com>
r92su: refactor names and locking

disconnect_bss_event is called from a irq context
and updated connect_bss. Therefore the mutex lock
does not protect the reference at all.

Signed-off-by: Christian Lamparter <chunkeey@googlemail.com>