[nrf fromlist] devicetree: Add DT_PROP_LAST macro

Add macro for getting the last element of an array type property.

Upstream PR #: 82133

Signed-off-by: Krzysztof Chruściński <[email protected]>

Author: nordic-krch

include/zephyr/devicetree.h

@@ -809,6 +809,17 @@
 #define DT_PROP_BY_IDX(node_id, prop, idx) \
 	DT_CAT5(node_id, _P_, prop, _IDX_, idx)
 
+/**
+ * @brief Get the last element of an array type property
+ *
+ * @param node_id node identifier
+ * @param prop lowercase-and-underscores property name
+ *
+ * @return a representation of the last element of the property
+ */
+#define DT_PROP_LAST(node_id, prop) \
+	DT_PROP_BY_IDX(node_id, prop, UTIL_DEC(DT_PROP_LEN(node_id, prop)))
+
 /**
  * @brief Like DT_PROP(), but with a fallback to @p default_value
  *