iio: chemical: bme680: Modify startup procedure

Modify the startup procedure to reflect the procedure of the Bosch BME68x
Sensor API. The initial readings and configuration of the sensor need to
happen in the following order:

1) Read calibration data [1,2]
2) Chip general configuration [3]
3) Gas configuration [4]

After the chip configuration it is necessary to ensure that the sensor is
in sleeping mode, in order to apply the gas configuration settings [5].

Also, after the soft reset, it is advised to wait for 5ms [6].

Link: https://github.com/boschsensortec/BME68x_SensorAPI/blob/v4.4.8/bme68x.c#L162 # [1]
Link: https://github.com/boschsensortec/BME68x_SensorAPI/blob/v4.4.8/examples/forced_mode/forced_mode.c#L44 # [2]
Link: https://github.com/boschsensortec/BME68x_SensorAPI/blob/v4.4.8/examples/forced_mode/forced_mode.c#L53 # [3]
Link: https://github.com/boschsensortec/BME68x_SensorAPI/blob/v4.4.8/examples/forced_mode/forced_mode.c#L60 # [4]
Link: https://github.com/boschsensortec/BME68x_SensorAPI/blob/v4.4.8/bme68x.c#L640 # [5]
Link: https://github.com/boschsensortec/BME68x_SensorAPI/blob/v4.4.8/bme68x.c#L294

 # [6]
Signed-off-by: Vasileios Amoiridis <vassilisamir@gmail.com>
Link: https://patch.msgid.link/20240609233826.330516-12-vassilisamir@gmail.com


Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>