staging: unisys: visorbus: combine response functions into a single one

There are several different controlvm response functions, consolidate them
to one so we can simplify error handling.

Signed-off-by: David Kershner <david.kershner@unisys.com>
Reviewed-by: Tim Sell <timothy.sell@unisys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>