software node: introduce PROPERTY_ENTRY_XXX_ARRAY_LEN()

Sometimes we want to initialize property entry array from a regular
pointer, when we can't determine length automatically via ARRAY_SIZE.
Let's introduce PROPERTY_ENTRY_XXX_ARRAY_LEN macros that take explicit
"len" argument.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>