drm/msm: Remove redundant null check

clk_prepare_enable() and clk_disable_unprepare() will check
NULL clock parameter, so It is not necessary to add additional checks.
Signed-off-by: Tian Tao <tiantao6@hisilicon.com>
Reviewed-by: Jordan Crouse <jcrouse@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@chromium.org>

drivers/gpu/drm/msm/msm_gpu.c

@@ -177,14 +177,11 @@ static int disable_clk(struct msm_gpu *gpu)
 
 static int enable_axi(struct msm_gpu *gpu)
 {
-	if (gpu->ebi1_clk)
-		clk_prepare_enable(gpu->ebi1_clk);
-	return 0;
+	return clk_prepare_enable(gpu->ebi1_clk);
 }
 
 static int disable_axi(struct msm_gpu *gpu)
 {
-	if (gpu->ebi1_clk)
 	clk_disable_unprepare(gpu->ebi1_clk);
 	return 0;
 }