There is no need to return failure (-EEXIST) when the requested
filter is already configured.
Fixes: d6cb17535f ("net/qede: fix VLAN filters")
Fixes: 77fac1b54f ("net/qede: fix filtering code")
Cc: stable@dpdk.org
Signed-off-by: Shahed Shaikh <shahed.shaikh@cavium.com>