cxgb4: fix missing unlock on ETHOFLD desc collect fail path

The label passed to the QDESC_GET for the ETHOFLD TXQ, RXQ, and FLQ, is the
'out' one, which skips the 'out_unlock' label, and thus doesn't unlock the
'uld_mutex' before returning. Additionally, since commit 5148e595
("cxgb4: add EOTID tracking and software context dump"), the access to
these ETHOFLD hardware queues should be protected by the 'mqprio_mutex'
instead.

Fixes: 2d0cb84d ("cxgb4: add ETHOFLD hardware queue support")
Fixes: 5148e595

 ("cxgb4: add EOTID tracking and software context dump")
Signed-off-by: Rafael Mendonca <rafaelmendsr@gmail.com>
Reviewed-by: Rahul Lakkireddy <rahul.lakkireddy@chelsio.com>
Link: https://lore.kernel.org/r/20220922175109.764898-1-rafaelmendsr@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>