iavf: fix double-release of rtnl_lock

iavf: fix double-release of rtnl_lock

[ Upstream commit f1340265726e0edf8a8cef28e665b28ad6302ce9 ]

This code does not jump to exit on an error in iavf_lan_add_device(),
so the rtnl_unlock() from the normal path will follow.

Fixes: b66c7bc1cd4d ("iavf: Refactor init state machine")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Tested-by: Konrad Jankowski <konrad0.jankowski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>