IDEX L1B TOF unit correction

[aldo9253]

The IDEX TOF channels are currently reporting pC and we need to change them to report pC/dt (currrent instead of charge).

[aldo9253]

I will try to address this in #3399 by 8/25.

[lacoak21]

@aldo9253 Please address it in a new PR. We try to do one PR per issue.

[aldo9253]

#3406