obs-ffmpeg: Disable VBAQ for H264 CQP rate control

Checks if rate control is CQP, if not, enable VBAQ. As per AMD, VBAQ
should not be used with CQP.

plugins/obs-ffmpeg/texture-amf.cpp

@@ -1286,7 +1286,8 @@ static bool amf_avc_init(void *data, obs_data_t *settings)
 	int rc = get_avc_rate_control(rc_str);
 
 	set_avc_property(enc, RATE_CONTROL_METHOD, rc);
-	set_avc_property(enc, ENABLE_VBAQ, true);
+	if (rc != AMF_VIDEO_ENCODER_RATE_CONTROL_METHOD_CONSTANT_QP)
+		set_avc_property(enc, ENABLE_VBAQ, true);
 
 	amf_avc_update_data(enc, rc, bitrate * 1000, qp);