Switch bladeRF sample format to SC16 Q11

The SC16 Q12 macro name was a misnomer that was marked deprecated and
replaced with a more appropriately named SC16 Q11 macro in 01/2014. The
deprecated SC16 Q12 macro was removed from libbladeRF in 10/1024.
Merge pull request #2 from jynik/master

Switch bladeRF sample format to SC16 Q11