power: qpnp-charger: change the kzalloc to devm_kzalloc in driver

Change the kzalloc allocations in the driver to devm_kzalloc
so that memory allocated with in probe function is automatically
freed on driver detach.

CRs-Fixed: 564898
Change-Id: I1edd08a0d08a6acbd0c1427ecc9f93c705d55f2f
Signed-off-by: Prasad Sodagudi <psodagud@codeaurora.org>