ASoC: omap: n810: Convert to clk_prepare_enable/clk_disable_unprepare

N810 audio driver has stopped working at some point. Probably when
OMAP2 was converted to common clock framework since now call to clk_enable
dumps the stack trace in drivers/clk/clk.c: __clk_enable() due
clk->prepare_count is zero.

Fix this by converting clk_enable/_disable calls to those that take care
of clock prepare/unprepare.

I'm not queueing this to linux-stable since OMAP2 common clock framework
conversion in commit ed1ebc4948fd ("ARM: OMAP2: clock: Convert to common clk")
happened before N810 was really usable in mainline and user base for N810 is
anyway small. Potential linux-stable candidates are only those after
commit 3d3a6d18abc6 ("watchdog: introduce retu_wdt driver").

Signed-off-by: Jarkko Nikula <jarkko.nikula@bitmer.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

sound/soc/omap/n810.c

@@ -100,12 +100,12 @@ static int n810_startup(struct snd_pcm_substream *substream)
 				     SNDRV_PCM_HW_PARAM_CHANNELS, 2, 2);
 
 	n810_ext_control(&codec->dapm);
-	return clk_enable(sys_clkout2);
+	return clk_prepare_enable(sys_clkout2);
 }
 
 static void n810_shutdown(struct snd_pcm_substream *substream)
 {
-	clk_disable(sys_clkout2);
+	clk_disable_unprepare(sys_clkout2);
 }
 
 static int n810_hw_params(struct snd_pcm_substream *substream,