power: pm8921-bms: fix the units of batt_temp for rbatt

The scaling factor tables has temperature in units of degree celcius.
The temperature passed to the get_rbatt function is in deci degree
celcius.

Convert the temperature to degree celcius before passing it to the
functions that read the scaling factor tables.

Change-Id: Iffb6a7c8d39ba7ececddadeb52913c3a19ee67bd
Signed-off-by: Abhijeet Dharmapurikar <adharmap@codeaurora.org>