mac80211: agg-tx: call drv_wake_tx_queue in proper context

Since drv_wake_tx_queue() is normally called in the TX path, which
is already in an RCU critical section, we should call it the same
way in the aggregation code path, so if the driver expects to be
able to use RCU, it'll already be protected without having to enter
a nested critical section.

Additionally, disable soft-IRQs, since not doing so could cause
issues in a driver that relies on them already being disabled like
in the other path.

Fixes: ba8c3d6f ("mac80211: add an intermediate software queue implementation")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>