staging: unisys: remove virthba driver for rewrite

The virthba driver is being rewritten and will be renamed to visorhba, so delete
the old driver from the source tree.

Signed-off-by: Benjamin Romer <benjamin.romer@unisys.com>
Reviewed-by: Don Zickus <dzickus@redhat.com>
Reviewed-by: Jes Sorensen <Jes.Sorensen@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>