This change is intended to make the bladeRF source/sink implementations
slightly more resilient to any transient issues in a flow graph.
For poor choices of buffers/transfers or under high CPU load, an RX or
TX operation might time out. Instead of immediately reporting WORK_DONE
and bailing out, an error message is now printed and the device will
attempt to continue transmitting/receiving samples.
After 3 consecutive errors have occurred on an RX/TX operation, the
device will report WORK_DONE; in this situation, something is likely
very wrong.