power: qg-soc: Allow SOC to increase only if we are charging

The current logic checks only for input presence to allow increase
in SOC. This check does not work well during hard JEITA conditions,
where input is present but device is not charging. Fix this
by making sure that we are indeed charging to allow SOC to scale up.

Change-Id: I649cbc136f404e44c78c6443d5586cbdeb0fd768
Signed-off-by: Anirudh Ghayal <aghayal@codeaurora.org>