Wrong frame rate when enabling external triggering after non-external triggering

[GruNyv]

If a camera has first been launched without enabling external triggering at a given frame rate and then the settings are changed to enable external triggering instead, then you need to unplug the power to the camera in order to get the correct frame rate.
Example:

1. is_triggered_flags is set to false and the frame rate is set to 10 fps.
2. Node is started and shutdown without disconnecting the power plug to the camera.
3. is_triggered_flags is set to true and an external triggering signal is sent at 20 Hz.

Expected behavior after step 3:
Camera is triggered at 20 Hz

Actual behavior:
Camera is triggered at ~6.7 Hz

[nkhedekar]

@nkhedekar @mnissov Check if fixed

[mnissov]

still seems to be a problem, repeating aforementioned testing procedure results in camera freq limited to 10 hz. Needs to be investigated.