mwifiex: remove stop_net_dev_queue operation in AP forwarding

Under uAP mode mwifiex may stop all net tx queues on forwarding
packets. This may stop some tx queues and they never have chance
to be waked up. There is also no need to check tx_pending and
stop queues here. Because local host has such kind of check when
transmitting packets and it's not proper to have forwarding affect
local transmitting.

Signed-off-by: Huawei Yang <harvey.huawei.yang@gmail.com>
Reviewed-by: Avinash Patil <patila@marvell.com>
Acked-by: Bing Zhao <bzhao@marvell.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>