Bring back the old qio mnt driver.

This now allows us to mount #s/cs onto /net.

Verified that
ash ifconfig
cs&
mount '#s/cs' /net

if you ls /net you will cs there.

If you run csquery, however, we're back to locking up. But at
least mount finishes again.

Signed-off-by: Ronald G. Minnich <rminnich@google.com>