Scheduling out and in for every FW message can slow us down
unnecessarily.  Our experiments show that even under heavy load
the FW responds to 99.9% messages within 200 us.  Add a short
busy wait before entering the wait queue.
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>