frameworks: Report 100% battery level

On devices without battery,the level is
reported as 0 which causes certain apps
which check battery level before executing
to fail.

The patch ensures that such apps work on devices
without battery driver.

Change-Id: I13b056ff52455f27de52ad1e459aa3d8c44b43a0
Signed-off-by: Vishal Bhoj <vishal.bhoj@linaro.org>