powerpc: Fix a number of sparse warnings

Address some of the trivial sparse warnings in arch/powerpc.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
index 6ecc38b..bde8b55 100644
--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c
@@ -907,7 +907,7 @@
 
 	if (ea >= spt->maxaddr)
 		return 0;
-	if (ea < 0x100000000) {
+	if (ea < 0x100000000UL) {
 		/* addresses below 4GB use spt->low_prot */
 		sbpm = spt->low_prot;
 	} else {