drm/amd/amdgpu: Add missing "DDR4" label

The commit d296278fd372003fc69588acfd0c0c5edbdf4874 added support for
detecting DDR4 but omitted the label that is printed out in
amdgpu_bo_init() resulting in a KASAN error.
Signed-off-by: NTom St Denis <tom.stdenis@amd.com>
Reviewed-by: NChristian König <christian.koenig@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_object.c

@@ -821,7 +821,8 @@ static const char *amdgpu_vram_names[] = {
 	"GDDR4",
 	"GDDR5",
 	"HBM",
-	"DDR3"
+	"DDR3",
+	"DDR4",
 };
 
 int amdgpu_bo_init(struct amdgpu_device *adev)