ACPI: property: Remove dead code

After the commit 3a7a2ab8 couple of functions became a dead code.
Moreover, for all these years nobody used them. Remove.

Fixes: 3a7a2ab8 ("ACPI / property: Extend fwnode_property_* to data-only subnodes")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>