drm/msm/mdp4: 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>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/20201231094155.25481-1-vulab@iscas.ac.cnSigned-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Rob Clark <robdclark@chromium.org>

drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.c

@@ -173,12 +173,9 @@ int mdp4_disable(struct mdp4_kms *mdp4_kms)
 	DBG("");
 
 	clk_disable_unprepare(mdp4_kms->clk);
-	if (mdp4_kms->pclk)
-		clk_disable_unprepare(mdp4_kms->pclk);
-	if (mdp4_kms->lut_clk)
-		clk_disable_unprepare(mdp4_kms->lut_clk);
-	if (mdp4_kms->axi_clk)
-		clk_disable_unprepare(mdp4_kms->axi_clk);
+	clk_disable_unprepare(mdp4_kms->pclk);
+	clk_disable_unprepare(mdp4_kms->lut_clk);
+	clk_disable_unprepare(mdp4_kms->axi_clk);
 
 	return 0;
 }
@@ -188,12 +185,9 @@ int mdp4_enable(struct mdp4_kms *mdp4_kms)
 	DBG("");
 
 	clk_prepare_enable(mdp4_kms->clk);
-	if (mdp4_kms->pclk)
-		clk_prepare_enable(mdp4_kms->pclk);
-	if (mdp4_kms->lut_clk)
-		clk_prepare_enable(mdp4_kms->lut_clk);
-	if (mdp4_kms->axi_clk)
-		clk_prepare_enable(mdp4_kms->axi_clk);
+	clk_prepare_enable(mdp4_kms->pclk);
+	clk_prepare_enable(mdp4_kms->lut_clk);
+	clk_prepare_enable(mdp4_kms->axi_clk);
 
 	return 0;
 }