Drivers: hv: utils: unify driver registration reporting

Unify driver registration reporting and move it to debug level as normally daemons write to syslog themselves
and these kernel messages are useless.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Tested-by: Alex Ng <alexng@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>