Add deprecation notices for various device drivers removed in 12.0.

This is a direct commit to stable/10 since these files have already
been removed in head.

MFC r260040:

In sys/dev/mcd/mcd.c, mark the static const COPYRIGHT string as __used,
so it ends up in the object file, and no warnings are emitted about it
being actually unused.

MFC r260040:

In sys/dev/mcd/mcd.c, mark the static const COPYRIGHT string as __used,
so it ends up in the object file, and no warnings are emitted about it
being actually unused.