power: fg-alg: Improve the accuracy of capacity learning algorithm

Capacity learning algorithm updates the capacity of battery
with every charge cycle that qualify the criterion for learning.
Improve the accuracy of capacity learning algorithm by adding the
capacity from rounded off part of the SOC to the learned capacity
value.

Change-Id: Ibd5f062de919bf22b06eb3cbf6e5d0fc89f343e8
Signed-off-by: Sahil Chandna <chandna@codeaurora.org>