fix mpu6050 sensor initialization issue

[Bartosz89k]

In my case the sensor (mpu6050), was not initialized correctly and returns erroneous data. The proposed changes works fine. In particular, I'm not sure why the second byte (0x80 == 1000 0000) is messing up the initialization. As I understand from the documentation (page 40): https://pdf1.alldatasheet.com/datasheet-pdf/view/1132807/TDK/MPU-6050.html the seventh bit of register 0x6b should be set to one: 0x80 = 1000 0000 but it doesn't work that way.

[lurch]

Related to #352 and the big discussion in #319 ?