power: qpnp-fg-gen4: cancel soc_scale_work conditionally

In FVSS, there is a possible path from which soc_scale_work
tries to cancel itself with cancel_work_sync and waits for itself
to complete. Fix this deadlock by cancelling soc_scale_work only when
it is not running.

Change-Id: Ie64d60643908cfab7812c3f0e23c7a7b78b6c44d
Signed-off-by: Sahil Chandna <chandna@codeaurora.org>