ACPI: property: Do not pass NULL handles to acpi_attach_data()

ACPI: property: Do not pass NULL handles to acpi_attach_data()

In certain circumstances, the ACPI handle of a data-only node may be
NULL, in which case it does not make sense to attempt to attach that
node to an ACPI namespace object, so update the code to avoid attempts
to do so.

This prevents confusing and unuseful error messages from being printed.

Also document the fact that the ACPI handle of a data-only node may be
NULL and when that happens in a code comment.  In addition, make
acpi_add_nondev_subnodes() print a diagnostic message for each data-only
node with an unknown ACPI namespace scope.

Fixes: 1d52f10917a7 ("ACPI: property: Tie data nodes to acpi handles")
Cc: 6.0+ <stable@vger.kernel.org> # 6.0+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Tested-by: Sakari Ailus <sakari.ailus@linux.intel.com>