ethdev: fix crash on owner delete

ethdev: fix crash on owner delete

'eth_dev->data' can be null before ethdev allocated. The API walks
through all eth devices, at least for some data can be null.

Adding 'eth_dev->data' null check before accessing it.

Fixes: 33c73aae32e4 ("ethdev: allow ownership operations on unused port")
Cc: stable@dpdk.org
Signed-off-by: Ferruh Yigit <ferruh.yigit@intel.com>
Acked-by: Chenbo Xia <chenbo.xia@intel.com>
Acked-by: Thomas Monjalon <thomas@monjalon.net>
Acked-by: Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>