power: bms/ccadc: move ccadc calibration to ccadc driver

There is a dependency for the CCADC calibration work on the BMS
driver. This prevents some devices that do not use the BMS
to utilize the CCADC.

Remove this dependency by moving the ccadc calibration
work to the CCADC driver to avoid this.

Change-Id: If43c781d6d2bc27f64dbbe594b6e81c5a5642f0b
Signed-off-by: David Keitel <dkeitel@codeaurora.org>