Staging: hv: match on DMI values to know if we should run.

The HV core mucks around with specific irqs and other low-level stuff
and takes forever to determine that it really shouldn't be running on a
machine.  So instead, trigger off of the DMI system information and
error out much sooner.  This also allows the module loading tools to
recognize that this code should be loaded on this type of system.

Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Hank Janssen <hjanssen@microsoft.com>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>