Reverse the processing order of assigned clocks property.

Linux processes these clocks in reverse order and some DT relies
on this fact. For example, the frequency setting for a given PLL
is the last in the list, preceded by the frequency setting of its
following divider or so...

MFC after:	1 week

sys/dev/extres/clk/clk.c

@@ -1407,7 +1407,7 @@ clk_set_assigned(device_t dev, phandle_t node)
 	if (ofw_bus_parse_xref_list_get_length(node,
 	    "assigned-clock-parents", "#clock-cells", &nparents) != 0)
 		nparents = -1;
-	for (i = 0; i < nclocks; i++) {
+	for (i = nclocks - 1; i >= 0; i--) {
 		/* First get the clock we are supposed to modify */
 		rv = clk_get_by_ofw_index_prop(dev, 0, "assigned-clocks",
 		    i, &clk);