device property: always check for fwnode type

Currently the property accessors unconditionally fall back to built-in property
set as a last resort. Make this strict and return an error in case the type of
fwnode is unknown.

This is actually a follow up to the commit 4fa7508e

 (device property:
Return -ENXIO if there is no suitable FW interface).

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>