device property: Drop redundant NULL checks

In cases when functions are called via fwnode operations,
we already know that this is software node we are dealing
with, hence no need to check if it's NULL, it can't be,

Reported-by: YE Chengfeng <cyeaa@connect.ust.hk>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20211026162954.89811-1-andriy.shevchenko@linux.intel.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>