Fix offset sign

[espindola]

When using calibrate_6022.py, the offset in the config file has the the opposite sign from the eeprom:

https://github.com/Ho-Ro/Hantek6022API/blob/01b82fd6a4bcb7bef5116a209e26206373521244/examples/calibrate_6022.py#L191

With this change I get much better agreement between the oscilloscope and the multimeter I calibrated it against.

[Ho-Ro]

I will doublecheck when I'm back at my desk and can do some measurements, thx for bringing up this issue.

[Ho-Ro]

I decided to correct the root cause of the reported behaviour and changed the sign in the ini file created by calibrate_6022.py. I didn't want to mess up the online-calibration from OpenHantek, because the sign handling of the offset looks consistent in hantekdsocontrol.cpp. Unfortunately you should either change the sign manually in your config file or redo the calibration and copy the offset part into your system ini file. But nevertheless I prefer to put the calibration data into EEPROM - this allows to move the scope to different computers and be always calibrated.

[espindola]

I decided to correct the root cause of the reported behaviour and changed the sign in the ini file created by calibrate_6022.py. I didn't want to mess up the online-calibration from OpenHantek, because the sign handling of the offset looks consistent in hantekdsocontrol.cpp. Unfortunately you should either change the sign manually in your config file or redo the calibration and copy the offset part into your system ini file. But nevertheless I prefer to put the calibration data into EEPROM - this allows to move the scope to different computers and be always calibrated.

Sounds good, thanks!