staging: unisys: cleanup iochannel includes

The iochannel.h file no longer needs to include
conttrolvmchannel.h, vbuschannel.h and vmcallinterfaces.h.

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