of/sparc: move is_root_node() to of.h

Rename is_root_node() to of_node_is_root() and make it available for
all archs to use, as it's not PROM-specific.

Signed-off-by: Andres Salomon <dilinger@queued.net>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
diff --git a/arch/sparc/kernel/prom_common.c b/arch/sparc/kernel/prom_common.c
index 57ac9e2..1f830da 100644
--- a/arch/sparc/kernel/prom_common.c
+++ b/arch/sparc/kernel/prom_common.c
@@ -244,7 +244,7 @@
 
 	n = prom_early_alloc(len);
 	strcpy(n, dp->parent->full_name);
-	if (!is_root_node(dp->parent)) {
+	if (!of_node_is_root(dp->parent)) {
 		strcpy(n + plen, "/");
 		plen++;
 	}