libbladeRF: Don't enable LMS DCCAL clocks when reading back DC cal values

The DCCAL clocks need to be enable when using DC_LOAD.

However, it appears that enabling the DCCAL clocks when reading back
values at later time yields intermittently corrupted read values
libbladeRF: Fixed flipped logic in version checks and an erroneous check

The implementations of these were the opposite of what is described
in the associated function descriptions.

Additionally, a version check was incorrectly testing the device's
firmware version instead of the FPGA version.
libbladerf: add meta support
libbladerf: add RX meta support
libbladerf: add TX meta support
libbladeRF: introduce optimal gain functions