The code that combines adjacent ranges for BIO_DELETEs to optimize
trims to the device assumes the list is sorted. Don't apply the
optimization of not sorting the queue when we have SSDs to the
delete_queue, since it causes more discard traffic to the drive. While
one could argue that the higher levels should coalesce the trims,
that's not done today, so some optimization at this level is needed.

CR: https://phabric.freebsd.org/D142