clk: sunxi: Support factor clocks with N factor starting not from 0

The PLLs on newer Allwinner SoC's, such as the A31 and A23, have a
N multiplier factor that starts from 1, not 0.

This patch adds an option to the factor clk driver's config data
structures to specify the base value of N.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>

drivers/clk/sunxi/clk-factors.c

@@ -62,7 +62,7 @@ static unsigned long clk_factors_recalc_rate(struct clk_hw *hw,
 		p = FACTOR_GET(config->pshift, config->pwidth, reg);
 
 	/* Calculate the rate */
-	rate = (parent_rate * n * (k + 1) >> p) / (m + 1);
+	rate = (parent_rate * (n + config->n_start) * (k + 1) >> p) / (m + 1);
 
 	return rate;
 }