libfdt: overlay: Fix comparison warning

With -Wsign-compare, compilers warn about a mismatching signedness in
a comparison in overlay_update_local_node_references().

This happens because the division of a signed int by an unsigned int
promotes the dividend to unsigned first (ANSI C standard 6.1.3.8).

As in this case we basically just divide by 4, we can do the division
separately earlier, which preserves the original type.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Message-Id: <20200921165303.9115-12-andre.przywara@arm.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

libfdt/fdt_overlay.c

@@ -241,6 +241,7 @@ static int overlay_update_local_node_references(void *fdto,
 
 		if (fixup_len % sizeof(uint32_t))
 			return -FDT_ERR_BADOVERLAY;
+		fixup_len /= sizeof(uint32_t);
 
 		tree_val = fdt_getprop(fdto, tree_node, name, &tree_len);
 		if (!tree_val) {
@@ -250,7 +251,7 @@ static int overlay_update_local_node_references(void *fdto,
 			return tree_len;
 		}
 
-		for (i = 0; i < (fixup_len / sizeof(uint32_t)); i++) {
+		for (i = 0; i < fixup_len; i++) {
 			fdt32_t adj_val;
 			uint32_t poffset;