mtd: core: add nvmem-partitions compatible to parse mtd as nvmem cells

Partitions that contains the nvmem-partitions compatible will register
their direct subonodes as nvmem cells and the node will be treated as a
nvmem provider.

Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com>

drivers/mtd/mtdcore.c

@@ -543,7 +543,7 @@ static int mtd_nvmem_add(struct mtd_info *mtd)
 	config.stride = 1;
 	config.read_only = true;
 	config.root_only = true;
-	config.no_of_node = true;
+	config.no_of_node = !of_device_is_compatible(node, "nvmem-partitions");
 	config.priv = mtd;
 
 	mtd->nvmem = nvmem_register(&config);