drm/amd/display: Check correct bounds for stream encoder instances for DCN303

[Why & How]
eng_id for DCN303 cannot be more than 1, since we have only two
instances of stream encoders.

Check the correct boundary condition for engine ID for DCN303 prevent
the potential out of bounds access.

Fixes: cd6d421e ("drm/amd/display: Initial DC support for Beige Goby")
Reported-by: NDan Carpenter <dan.carpenter@oracle.com>
Cc: stable@vger.kernel.org
Reviewed-by: NChris Park <Chris.Park@amd.com>
Reviewed-by: NRodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Acked-by: NTom Chung <chiahsuan.chung@amd.com>
Signed-off-by: NAurabindo Pillai <aurabindo.pillai@amd.com>
Tested-by: NDaniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/dcn303/dcn303_resource.c

@@ -372,7 +372,7 @@ static struct stream_encoder *dcn303_stream_encoder_create(enum engine_id eng_id
 	int afmt_inst;
 
 	/* Mapping of VPG, AFMT, DME register blocks to DIO block instance */
-	if (eng_id <= ENGINE_ID_DIGE) {
+	if (eng_id <= ENGINE_ID_DIGB) {
 		vpg_inst = eng_id;
 		afmt_inst = eng_id;
 	} else