[peripherals] mpu60x0_i2c: only copy ext data if i2c_bypass is false
[imu] fixes for imu_drotek_10dof_v2

- fix copying of unscaled gyro/accel data
- make i2c addresses of mpu and hmc configurable
- change orientation so z-axis is down when chips face up: define IMU_DROTEK_2_ORIENTATION_IC_UP
- silence some warnings