omapfb/dss: Remove redundant null check before clk_prepare_enable/clk_disable_unprepare

Because clk_prepare_enable() and clk_disable_unprepare() already checked
NULL clock parameter, so the additional checks are unnecessary, just
remove them.
Signed-off-by: Xu Wang <vulab@iscas.ac.cn>
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20201014084920.25813-1-vulab@iscas.ac.cn

drivers/video/fbdev/omap2/omapfb/dss/venc.c

@@ -890,8 +890,7 @@ static int venc_remove(struct platform_device *pdev)
 
 static int venc_runtime_suspend(struct device *dev)
 {
-	if (venc.tv_dac_clk)
-		clk_disable_unprepare(venc.tv_dac_clk);
+	clk_disable_unprepare(venc.tv_dac_clk);
 
 	dispc_runtime_put();
 
@@ -906,8 +905,7 @@ static int venc_runtime_resume(struct device *dev)
 	if (r < 0)
 		return r;
 
-	if (venc.tv_dac_clk)
-		clk_prepare_enable(venc.tv_dac_clk);
+	clk_prepare_enable(venc.tv_dac_clk);
 
 	return 0;
 }