bq20z75: Fix time and temp units

Corrected temperature and time to empty/full conversions.
Temperature is in 0.1°C, time is in seconds.

Corrected units in comment. "Convert to µWh."

Signed-off-by: Benson Leung <bleung@chromium.org>
Acked-by: Rhyland Klein <rklein@nvidia.com>
Signed-off-by: Anton Vorontsov <cbouatmailru@gmail.com>