Add clock control hackrf_debug

hackrf_sweep: report sweep rate instead of data rate

hackrf_sweep: suppress ifft output unless requested

hackrf_sweep: corrected output file descriptors in binary and ifft modes for compatibility with output file option

hackrf_sweep: Added experimental Inverse FFT binary output mode.

Disable CLK7 and power down CLK6/7 to reduce emissions

Merge pull request #351 from schneider42/rad1o-clocks

hackrf_sweep: avoid starting RX too early

fix(rad1o): Restore old clock behaviour for now.

Reinstate LPC4330 linker script