iio: chemical: bme680: use s16 variable for temp value to avoid casting

Use local s16 variable for the temperature channel to avoid casting it
later before passing it to the bme680_read_temp() function. This way,
possible endianness and initialization issues are avoided.

Signed-off-by: Vasileios Amoiridis <vassilisamir@gmail.com>
Link: https://patch.msgid.link/20241030235424.214935-2-vassilisamir@gmail.com


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