dpaa_eth: fix the access method for the dpaa_napi_portal

dpaa_eth: fix the access method for the dpaa_napi_portal

The current use of container_of is flawed and unnecessary. Obtain
the dpaa_napi_portal reference from the private percpu data instead.

Fixes: a1e031ffb422 ("dpaa_eth: add XDP_REDIRECT support")
Reported-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Camelia Groza <camelia.groza@nxp.com>
Acked-by: Madalin Bucur <madalin.bucur@oss.nxp.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Link: https://lore.kernel.org/r/20210218182106.22613-1-camelia.groza@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>