Starting with voxl-suite 0.3.4 (what you have installed) voxl_cam_ros is deprecated due to annoyances like this.
Please try its replacement node voxl_mpa_to_ros. This will publish all cameras, IMU, and some other data to ROS all with one node!
yocto:/# roslaunch voxl_mpa_to_ros voxl_mpa_to_ros.launch
in another window:
yocto:/# rostopic list
Don't worry, it won't actually publish data until something subscribes to the topic so it's not wasting CPU having all those topics advertised.