Revert r363123.

As Emanuel poited me the Linux processes these clock assignments in forward
order, not in reversed. I misread the original code.
Tha problem with wrong order for assigned clocks found in tegra (and some imx)
DT should be reanalyzed and solved by different way.

MFC with:	r363123
Reported by;	manu

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 = nclocks - 1; i >= 0; i--) {
+	for (i = 0; i < nclocks; i++) {
 		/* First get the clock we are supposed to modify */
 		rv = clk_get_by_ofw_index_prop(dev, 0, "assigned-clocks",
 		    i, &clk);