Drivers: hv: vmbus: Use the standard format string to format GUIDs

Format GUIDS as per MSFT standard. This makes interacting with MSFT
tool stack easier.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com>
Reviewed-by: Olaf Hering <olaf@aepfle.de>
Reviewed-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>