UPSTREAM: mac80211: set NETIF_F_LLTX when using intermediate tx queues

When using iTXQ, tx sequence number allocation and statistics are run at
dequeue time. Because of that, it is safe to enable NETIF_F_LLTX, which
allows tx handlers to run on multiple CPUs in parallel.

(cherry picked from commit 8dbb000e)
(source: https://git.kernel.org/cgit/linux/kernel/git/kvalo/ath.git

)

BUG=b:132147953
TEST=None

Change-Id: I09d0857a1d539b25e1b74eda0163daf77650a7c4
Signed-off-by: Felix Fietkau <nbd@nbd.name>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Tamizh chelvam <tamizhr@codeaurora.org>
Signed-off-by: Vamsi Singamsetty <vamssi@codeaurora.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/1643394


Reviewed-by: Julan Hsu <julanhsu@google.com>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Tested-by: Julan Hsu <julanhsu@google.com>
Legacy-Commit-Queue: Commit Bot <commit-bot@chromium.org>