clk: sun6i: Protect SDRAM gating bit

Prevent the SDRAM controller from being gated by force-enabling it in the
machine code.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Acked-by: Mike Turquette <mturquette@linaro.org>
Signed-off-by: Emilio López <emilio@elopez.com.ar>

drivers/clk/sunxi/clk-sunxi.c

@@ -1227,6 +1227,7 @@ CLK_OF_DECLARE(sun7i_a20_clk_init, "allwinner,sun7i-a20", sun5i_init_clocks);
 
 static const char *sun6i_critical_clocks[] __initdata = {
 	"cpu",
+	"ahb1_sdram",
 };
 
 static void __init sun6i_init_clocks(struct device_node *node)