drm/amdgpu: fix memory leak during TDR test(v2)

fix system memory leak

v2:
fix coding style
Signed-off-by: Monk Liu <Monk.Liu@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/powerplay/smu_v11_0.c

@@ -978,8 +978,12 @@ int smu_v11_0_init_max_sustainable_clocks(struct smu_context *smu)
 	struct smu_11_0_max_sustainable_clocks *max_sustainable_clocks;
 	int ret = 0;
 
+	if (!smu->smu_table.max_sustainable_clocks)
 		max_sustainable_clocks = kzalloc(sizeof(struct smu_11_0_max_sustainable_clocks),
 					 GFP_KERNEL);
+	else
+		max_sustainable_clocks = smu->smu_table.max_sustainable_clocks;
+
 	smu->smu_table.max_sustainable_clocks = (void *)max_sustainable_clocks;
 
 	max_sustainable_clocks->uclock = smu->smu_table.boot_values.uclk / 100;