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>
diff --git a/arch/riscv/lib/andes_plic.c b/arch/riscv/lib/andes_plic.c
index 5e113ee..6851475 100644
--- a/arch/riscv/lib/andes_plic.c
+++ b/arch/riscv/lib/andes_plic.c
@@ -71,7 +71,7 @@
 			continue;
 
 		/* skip if hart is marked as not available */
-		if (!ofnode_is_available(node))
+		if (!ofnode_is_enabled(node))
 			continue;
 
 		/* read hart ID of CPU */