blk-mq: don't call into depth limiting for reserved tags

It's not useful, they are internal and/or error handling recovery
commands.

Acked-by: Paolo Valente <paolo.valente@linaro.org>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
1 file changed