Arrange for the ASIC-H4 SPI bus activity be run at 20mA

The default ASIC->H4 SPI driver currents are 4 mA. Eddie Bergeron pointed out those could be configured run to at 20mA. That said, we do not want to add any heat at the FPA. Also, other thermo-mechanical changes have evidently fixed the problem this addresses.

We only generate traffic on that bus when the main ASIC reconfiguration command is run, which we only do when powering the system up or when doing unusual engineering (changing the number of readout channels, IRP selection, windowed readout).

So we can wrap that command by changing the SPI driver currents from 4 to 20 mA and back to 4mA.