MFS of fix to twe(4) driver. Fixes problem seen on 6xxx series controllers
where driver repeatedly submits the same request if the cmd queue gets
full. This will be handled as an Errata Notice.

Commits being MFS-ed:
sys/dev/twe/twe.c 1.1.2.10
sys/dev/twe/twe_freebsd.c 1.2.2.9
sys/dev/te/twevar.h 1.1.2.8

Submitted by: ps, vkashyap
Reviewed by: re
Approved by: so