iio: pressure: bmp280: Add SCALE, RAW values in channels and refactorize them

Add extra IIO_CHAN_INFO_SCALE and IIO_CHAN_INFO_RAW channels in order
to be able to calculate the processed value with standard userspace
IIO tools. Can be used for triggered buffers as well.

Even though it is not a good design choice to have SCALE, RAW and
PROCESSED together, the PROCESSED channel is kept for ABI compatibility.

While at it, separate BMPxxx and BMExxx device channels since BME
supports also humidity measurements.

Signed-off-by: Vasileios Amoiridis <vassilisamir@gmail.com>
Link: https://lore.kernel.org/r/20240512230524.53990-5-vassilisamir@gmail.com
Link: https://patch.msgid.link/20240628171726.124852-3-vassilisamir@gmail.com


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