UPSTREAM: driver core: Rename dev_links_info.defer_sync to defer_hook

The defer_sync field is used as a hook to add the device to the
deferred_sync list. Rename it so that it's more meaningful for the next
patch that'll also use this field as a hook to a deferred_fw_devlink
list.

Signed-off-by: Saravana Kannan <saravanak@google.com>
Reviewed-by: Rafael J. Wysocki <rafael@kernel.org>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20200701194259.3337652-3-saravanak@google.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit ec7bd78498f29680f536451fbdf9464e851273ed)
Signed-off-by: Saravana Kannan <saravanak@google.com>
Bug: 157691602
Change-Id: Ia213a9b8b6efc33882f5b2cfaad284ee0eca8cd4