pm8001: fix a memory leak in flash_update

ccb->fw_control_context is copied to local fw_control_context and
the local variable is never used later

Free ccb->fw_control_context.  The task is forgotten thus also the
reference to fw_control_context and the completion thread takes the info
from virt_ptr again.

Signed-off-by: Tomas Henzl <thenzl@redhat.com>
Acked-by: Suresh Thiagarajan <Suresh.Thiagarajan@pmcs.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>