arm64: defconfig: enable bpf/cgroup firewalling

This avoids the following systemd warning:

[    2.618538] systemd[1]: system-getty.slice: unit configures an IP
 firewall, but the local system does not support BPF/cgroup firewalling.
[    2.630916] systemd[1]: (This warning is only shown for the first
 unit using IP firewalling.)

Signed-off-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
Acked-by: Song Liu <songliubraving@fb.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>