FMC connector: don't connect VREF_A_M2C (pin h1)
This mezzanine does not use I/O standard that would require VREF, so according to FMC standard VREF can be left unconnected. In addition, connecting this pin to 3V3 means e.g. when this mezzanine is plugged on non-rad-tol System Board, we would be feeding 3V3 to a HP (high performance, low-voltage) I/O bank of ZU7.