power: qpnp-fg-gen3: Fix FG shutdown path

Remove cleanup functionality from FG shutdown hook as there is a
possibility of resources being used as part of power_supply callbacks
during reboot/shutdown.

Change-Id: I5f1f4528664c5917536de037fc4045f0f6da08dd
Signed-off-by: Sahil Chandna <chandna@codeaurora.org>