staging: unisys: visorchannel: remove redundant member size

Removes size member from the visorchannel struct, since it was
a duplicate of the nbytes member.

Signed-off-by: David Binder <david.binder@unisys.com>
Signed-off-by: David Kershner <david.kershner@unisys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>