power: qpnp-linear-charger: Fix mutex deadlock in charger

There is a deadlock condition between BMS reporting end-of-charge
and charger driver resuming charging in get capacity.

Fix the above deadlock by calling get capacity outside the
mutex lock.

CRs-Fixed: 675064
Change-Id: I385bfc301bd55d5460d2294a8427d31648df9bb6
Signed-off-by: Ashay Jaiswal <ashayj@codeaurora.org>