Staging: hv: typedef removal for VmbusApi.h

The function pointers still have ugly names, but the structures
are now cleaned up.

Note, a comment was added where the driver structure is pointing
at a problem that needs to be fixed up later in the code.

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