libbladeRF: [WIP] Additional API header updates and touch-ups
libbladeRF: [WIP] Acquire per-module locks on sync calls

Synchronous data transfer functions now hold a per-device-module lock
when executing to ensure these operations are carried out atomically.

The control lock is also held during sync configuration, as upcoming
changes to introduce metadata support will require flipping some config
bits on the FPGA during this operation.
libbladeRF: [WIP] Hold control lock while (de)initializing stream