drm/exynos: gsc: prepare and unprepare gsc clock

Ths patch changes the clk_enable and clk_disable call in gsc driver
into clk_prepare_enable and clk_disable_unprepare.

Signed-off-by: Seung-Woo Kim <sw0312.kim@samsung.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Signed-off-by: Inki Dae <inki.dae@samsung.com>

drivers/gpu/drm/exynos/exynos_drm_gsc.c

@@ -1215,10 +1215,10 @@ static int gsc_clk_ctrl(struct gsc_context *ctx, bool enable)
 	DRM_DEBUG_KMS("enable[%d]\n", enable);
 
 	if (enable) {
-		clk_enable(ctx->gsc_clk);
+		clk_prepare_enable(ctx->gsc_clk);
 		ctx->suspended = false;
 	} else {
-		clk_disable(ctx->gsc_clk);
+		clk_disable_unprepare(ctx->gsc_clk);
 		ctx->suspended = true;
 	}