libbladeRF/tests: Fixed dead code (CID1232253), fixed samplerate range

Removed unnecessary check for low sample rate; this cannot occur.

Fixed the random range to not be so biased toward clamping to the max
sample rate.
libbladeRF/tests: Fixed dead code (CID1232254), fixed bandwidth range

Removed unnecessary check for low bandwidth; this cannot occur.

Fixed random range to not be so biased toward clamping to the max bw.
libbladeRF: Fixed memory leak in error condition (CID1232258)
libbladeRF/tests: Fixed memory leak in error condition (CID1232259)
bladeRF-cli: Fixed memory leak in error condition (CID1234624)