dc.c:use kzalloc without test

dc.c:583:null check is needed after using kzalloc function
Reviewed-by: NHarry Wentland <harry.wentland@amd.com>
Signed-off-by: Nzhongshiqi <zhong.shiqi@zte.com.cn>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/core/dc.c

@@ -580,6 +580,10 @@ static bool construct(struct dc *dc,
 #ifdef CONFIG_DRM_AMD_DC_DCN2_0
 	// Allocate memory for the vm_helper
 	dc->vm_helper = kzalloc(sizeof(struct vm_helper), GFP_KERNEL);
+	if (!dc->vm_helper) {
+		dm_error("%s: failed to create dc->vm_helper\n", __func__);
+		goto fail;
+	}
 
 #endif
 	memcpy(&dc->bb_overrides, &init_params->bb_overrides, sizeof(dc->bb_overrides));