OptoHybrid FPGA slow-control GBT phase scan

Description

As for the VFAT e-links, the OH FPGA e-link requires to have the proper GBT RX phase set in order to establish reliable communication. Such a phase scan is also helpful in debugging various communication-related issues.

Possible fixes

An OH FPGA slow-control phase scan routine is implemented in a similar way than for the VFAT, for both GE1/1 and GE2/1. The GBT RX phase is scanned from the minimum to the maximum and slow-control communication with the OH FPGA is ensured via many register accesses (typically reads from and writes to CONTROL.LOOPBACK.DATA). Sending L1A to the OH FPGA should also be possible in order to increase the robustness of the scan.

The feature is exposed in the web interface next to the VFAT GBT phase scan. One can think about check-boxes in order to select which components have to be scanned.