sh: clkfwk: rate table construction and rounding for SH7785.

This adds support for constructing a rate table by looking at potential
divisors for a specified clock. Each FQRMR clock is given its own table.
Presently each table is rebuilt when the parent propagates down a new
rate, so some more logic needs to be added to do this more intelligently.

Additionally, a fairly generic round_rate() implementation is then
layered on top of it, which subsequently provides us with cpufreq support.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

arch/sh/kernel/cpu/clock.c

@@ -63,6 +63,9 @@ void propagate_rate(struct clk *tclk)
 	list_for_each_entry(clkp, &tclk->children, sibling) {
 		if (clkp->ops && clkp->ops->recalc)
 			clkp->rate = clkp->ops->recalc(clkp);
+		if (clkp->ops && clkp->ops->build_rate_table)
+			clkp->ops->build_rate_table(clkp);
+
 		propagate_rate(clkp);
 	}
 }