net/virtio: fix aarch32 build

net/virtio: fix aarch32 build

NEON vector path of the PMD needs aarch64 support. But it was
enabled for aarch32 build as well because aarch32 build had
cpu_family set to aarch64. So build for aarch32 will fail due
to unsupported intrinsics.

Fix aarch32 build by updating meson file to exclude NEON vector
implementation for aarch32.

Fixes: 749799482a72 ("net/virtio: add to meson build")
Cc: stable@dpdk.org
Signed-off-by: Juraj Linkeš <juraj.linkes@pantheon.tech>
Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>