iavf: Fix a locking bug in an error path

If the netdev lock has been obtained, unlock it before returning.
This bug has been detected by the Clang thread-safety analyzer.

Fixes: afc66498 ("eth: iavf: extend the netdev_lock usage")
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Link: https://patch.msgid.link/20250206175114.1974171-28-bvanassche@acm.org


Signed-off-by: Jakub Kicinski <kuba@kernel.org>