[Firmware] FPGA is reset when performing flash operations

[jynik]

It appears that the FPGA is becoming unloaded when performing flash operations.

To reproduce:

1. Load FPGA
2. Flash firmware or backup calibration data via the bladeRF-cli
3. Observe change in LEDs, denoting the FPGA state

This, coupled with issue #195 yields a rather inconvenient situation.

Current workaround is to reload the FPGA after flash operations.