[BPMApp] Not checking if acquisition is stalled due to too fast data rates

[lerwys]

Problem: By changing the ADC clock frequency one can be in a condition where the maximum DDR3 memory bandwidth is exceeded. At least a flag indicating this has happened with the current acquisition must be created.

Solution: There is already a flag in the lnls-bpm/bpm-gw gateware and lnls-bpm/halcs software that can be used for this., called FC_FULL status field in the acquisition status register.

This is related to issue #28.