Remap incorrect b2 amps

A b2 cable at the FPA was misfired, and amps 1_2 and 0_1 are swapped. Add a fix.

I'll add a single place for massaging post-readout images, but will not add any general amp-swapping routine or configuration – I really do not think we will see this particular issue anywhere else, but would not be surprised if we ran into some other error which we will need to cleanup with other cameras.