libbladeRF: Normalize the DC offset set/get functions to +/- 2048, update comments to reflect this.
libbladeRF: Add in additional error checking on correction ranges.  Do scaling for RX and TX independently.
libbladeRF: Format all comments with /* */, fix capitalization.
Merge pull request #208 from modustollens/modus-dev-issue_202

Merge modus's DC correction fixes to libbladeRF v0.12.0