Long pause every time frequency is changed

[argilo]

#49 has made SoapyRTLSDR unusable in Gqrx because reception is interrupted for approximately one second every time the frequency is adjusted.

@cjcliffe Can you let me know what the bug was that prompted #49? I'd be happy to help find a better solution for it.

[guruofquality]

This bug that caused this was reverted, it will be in the next tag: 60b41d5