Staging: hv: remove VMBUS_MSGINFO typedef

Note that this struct doesn't appear to be used anywhere and can
probably be removed.

Signed-off-by: Bill Pemberton <wfp5p@virginia.edu>
Cc: Hank Janssen <hjanssen@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>