Fixing (hopefully) bandwidth detection for 24 kHz analysis

The masking term was previously completely broken (even in 1.1). The
bandwidth detection relies mostly on the noise floor and can only use
masking to cut one extra band. The 12-24 kHz energy is now normalized properly
but uses a higher noise floor due to the leakage in the resampler. Bandwidth
detection is still mostly useless at identifying SWB speech (it usually says
FB).