ARM: i.MX6: Enable parent propagation for clk_gate2

Enable parent rate propagation for clk_gate2 to allow the
clock consumers to adjust their rates.
One effect of this is that the i.MX6 NAND controller now can adjust
its rate. It already called a clk_set_rate(rate, 96000000), but this
had no effect, so the clock stayed at reset default 24MHz resulting
in a rather slow timing. This became a problem when commit
"1daa3bc mtd: nand_mxs: Setup timing" introduced EDO timing mode for
faster NAND chips. EDO mode can only work properly for cycle times
< 30ns (at least that's specified in the ONFI spec). 1daa3bc resulted
in sporadic NAND read errors on some boards.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Tested-by: Sam Ravnborg <sam@ravnborg.org>

arch/arm/mach-imx/clk-gate2.c

@@ -79,6 +79,8 @@ static int clk_gate2_is_enabled(struct clk *clk)
 }
 
 static struct clk_ops clk_gate2_ops = {
+	.set_rate = clk_parent_set_rate,
+	.round_rate = clk_parent_round_rate,
 	.enable = clk_gate2_enable,
 	.disable = clk_gate2_disable,
 	.is_enabled = clk_gate2_is_enabled,
@@ -96,6 +98,7 @@ struct clk *clk_gate2_alloc(const char *name, const char *parent,
 	g->clk.name = name;
 	g->clk.parent_names = &g->parent;
 	g->clk.num_parents = 1;
+	g->clk.flags = CLK_SET_RATE_PARENT;
 
 	return &g->clk;
 }