OMAPDSS: add clk_prepare_enable and clk_disable_unprepare

In preparation of OMAP moving to Common Clk Framework(CCF) change
clk_enable() and clk_disable() calls to clk_prepare_enable() and
clk_disable_unprepare() in omapdss. This can be safely done, as omapdss
never enables or disables clocks in atomic context.

Signed-off-by: Rajendra Nayak <rnayak@ti.com>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: <linux-fbdev@vger.kernel.org>
Cc: Paul Walmsley <paul@pwsan.com>
Cc: Mike Turquette <mturquette@linaro.org>
[tomi.valkeinen@ti.com: updated patch description]
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
diff --git a/drivers/video/omap2/dss/hdmi.c b/drivers/video/omap2/dss/hdmi.c
index 8195c71..b9424b3 100644
--- a/drivers/video/omap2/dss/hdmi.c
+++ b/drivers/video/omap2/dss/hdmi.c
@@ -785,7 +785,7 @@
 
 static int hdmi_runtime_suspend(struct device *dev)
 {
-	clk_disable(hdmi.sys_clk);
+	clk_disable_unprepare(hdmi.sys_clk);
 
 	dispc_runtime_put();
 
@@ -800,7 +800,7 @@
 	if (r < 0)
 		return r;
 
-	clk_enable(hdmi.sys_clk);
+	clk_prepare_enable(hdmi.sys_clk);
 
 	return 0;
 }