power: vm-bms: Modify the function names for batterydata interface

Modify the function names of batterydata interface to avoid conflict with
the qg battery interface as it uses the same names.

Change-Id: I4ea1b91c664d920d20e0a588901138e27bbe5bb8
Signed-off-by: Kavya Nunna <knunna@codeaurora.org>