of: reserved-memory: ignore disabled memory-region nodes

Ignore disabled nodes in the memory-region
nodes list and continue to initialize the rest
of enabled nodes.

Check if the "reserved-memory" node is available
and if it's not available, return 0 to ignore the
"reserved-memory" node and continue parsing with
next node in memory-region nodes list.

Signed-off-by: Krishna Reddy <[e-mail]>
Signed-off-by: Puneet Saxena <[e-mail]>
Signed-off-by: Rob Herring <[e-mail]>

drivers/of/of_reserved_mem.c

···
 	if (!target)
 		return -ENODEV;
 
+	if (!of_device_is_available(target))
+		return 0;
+
 	rmem = __find_rmem(target);
 	of_node_put(target);