ACPI: property: restore _DSD data subnodes GUID comment

Commit 5f5e4890 ("ACPI / property: Allow multiple property
compatible _DSD entries") removed the comment of _DSD data subnodes
GUID.  Restore it.

Fixes: 5f5e4890

 ("ACPI / property: Allow multiple property compatible _DSD entries")
Signed-off-by: Shunyong Yang <shunyong.yang@hxt-semitech.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>