ab8500-btemp: Defer btemp filtering while initialising

Due to btemp filtering enabled during init, temp values reported
to charge algorithm driver started from 0. As a result,charge
algorithm was going into wrong state and charging was stopped.

Signed-off-by: Rupesh Kumar <rupesh.kumar@stericsson.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Reviewed-by: Marcus COOPER <marcus.xm.cooper@stericsson.com>
Reviewed-by: Martin SJOBLOM <martin.w.sjoblom@stericsson.com>
Reviewed-by: Philippe LANGLAIS <philippe.langlais@stericsson.com>