Small linhpsd fixes

https://github.com/enthru/linhpsdr

Didn’t touched it for a long time. But now, as I ordered 2m transverter, it’s time to fix some FM mod. issues in this fork.

What’s fixed:

1. Auto disabling squelch when non FM mode chosen
2. Disable squelch in NFM mode if setting for squelch of too low (there is no button for squelch so using just squelch bar to disable it)
3. Fixed deviation select for NFM in receiver window