dm: core: Drop ofnode_is_available()

This function is also available as ofnode_is_enabled(), so use that
instead.

Signed-off-by: Simon Glass <sjg@chromium.org>

include/dm/ofnode.h

@@ -872,14 +872,6 @@ int ofnode_next_property(struct ofprop *prop);
 const void *ofprop_get_property(const struct ofprop *prop,
 				const char **propname, int *lenp);
 
-/**
- * ofnode_is_available() - check if a node is marked available
- *
- * @node: node to check
- * Return: true if node's 'status' property is "okay" (or is missing)
- */
-bool ofnode_is_available(ofnode node);
-
 /**
  * ofnode_get_addr_size() - get address and size from a property
  *