drm/amd/display: Disable dmcu fw loading for dcn314

[Why]
DCN 3.1.4 uses dmub not dmcu. Attempt to identify
dmcu firmware for dcn314 results in dm init error:
"Unsupported ASIC type"

[How]
Add dcn314 to the list of asics that don't require dmcu
Signed-off-by: Roman Li <roman.li@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

@@ -1805,6 +1805,7 @@ static int load_dmcu_fw(struct amdgpu_device *adev)
 		case IP_VERSION(3, 0, 1):
 		case IP_VERSION(3, 1, 2):
 		case IP_VERSION(3, 1, 3):
+		case IP_VERSION(3, 1, 4):
 		case IP_VERSION(3, 1, 5):
 		case IP_VERSION(3, 1, 6):
 		case IP_VERSION(3, 2, 0):