samplerate and sample format tweaks

[enkidu]

Hello, While playing with your offline tools (gps-sdr-sim and limeplayer) I found, that 1-bit I/Q with 1MSps works best even with Galaxy phones, however gain has to be decreased evel below 0.1 (got nice results with 0.04). Of course warning about failed callibration persist, but it is limeutil bug/feature.