common/fdt_support.c: avoid unintended return from fdt_fixup_memory_banks()

fdt_fixup_memory_banks() will add and update /memory node in
device tree blob. In the case that /memory node doesn't exist,
after adding a new one, this function returns error.

The correct behavior should be continuing to update its properties.

Signed-off-by: Miao Yan <miao.yan@windriver.com>
diff --git a/common/fdt_support.c b/common/fdt_support.c
index 1f0d8f5..4e32b02 100644
--- a/common/fdt_support.c
+++ b/common/fdt_support.c
@@ -400,10 +400,11 @@
 	nodeoffset = fdt_path_offset(blob, "/memory");
 	if (nodeoffset < 0) {
 		nodeoffset = fdt_add_subnode(blob, 0, "memory");
-		if (nodeoffset < 0)
+		if (nodeoffset < 0) {
 			printf("WARNING: could not create /memory: %s.\n",
 					fdt_strerror(nodeoffset));
-		return nodeoffset;
+			return nodeoffset;
+		}
 	}
 	err = fdt_setprop(blob, nodeoffset, "device_type", "memory",
 			sizeof("memory"));