iio: fix center temperature of bmc150-accel-core

The center temperature of the supported devices stored in the constant
BMC150_ACCEL_TEMP_CENTER_VAL is not 24 degrees but 23 degrees.

It seems that some datasheets were inconsistent on this value leading
to the error.  For most usecases will only make minor difference so
not queued for stable.

Signed-off-by: Pascal Bouwmann <bouwmann@tau-tec.de>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>