Removal of pre-NEWBUS sound driver / speaker-drivers

[Joerg Sonnenberger]

Hi all,
the patch at http://leaf.dragnflybsd.org/~joerg/isa-sound.diff
removes all the pre-NEWBUS drivers and pca and speaker. The latter
don't play well with the default timer settings and are IMO a waste
of time until someone explicitly steps up and brings them into modern
age.

Matt, I'd like to have this in the release, I'd like to use device snd
for something else soon :)

Joerg