Fix this to avoid build problems if DRM_AMD_DC_DCN3_02 is defined, but
DRM_AMD_DC_DCN3_01 is not.

Fixes: 36d26912 ("drm/amd/display: Add support for DCN302 (v2)")
Acked-by: Nirmoy Das <nirmoy.das@amd.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>