[media] exynos-gsc: Do full clock gating at runtime PM suspend

To potentially save more power in runtime PM suspend state, let's
also prepare/unprepare the clock from the runtime PM callbacks.

[mszyprow: rebased onto v4.9-rc4]
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Tested-by: Javier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

drivers/media/platform/exynos-gsc/gsc-core.c

@@ -1154,7 +1154,7 @@ static int gsc_runtime_resume(struct device *dev)
 
 	pr_debug("gsc%d: state: 0x%lx", gsc->id, gsc->state);
 
-	ret = clk_enable(gsc->clock);
+	ret = clk_prepare_enable(gsc->clock);
 	if (ret)
 		return ret;
 
@@ -1172,7 +1172,7 @@ static int gsc_runtime_suspend(struct device *dev)
 
 	ret = gsc_m2m_suspend(gsc);
 	if (!ret)
-		clk_disable(gsc->clock);
+		clk_disable_unprepare(gsc->clock);
 
 	pr_debug("gsc%d: state: 0x%lx", gsc->id, gsc->state);
 	return ret;