examples: add eal cleanup to examples

examples: add eal cleanup to examples

According to the programming guide, the rte_eal_init should be used pairs
with rte_eal_cleanup.

This patch add rte_eal_cleanup to examples to encourage new users of
DPDK to use it.

Fixes: aec9c13c5257 ("eal: add function to release internal resources")
Fixes: 3d0fad56b74a ("examples/fips_validation: add crypto FIPS application")
Fixes: c8e6ceecebc1 ("examples/ioat: add new sample app for ioat driver")
Fixes: 4ff457986f76 ("examples/l2fwd-event: add default poll mode routines")
Fixes: 08bd1a174461 ("examples/l3fwd-graph: add graph-based l3fwd skeleton")
Fixes: c5eebf85badc ("examples/ntb: add example for NTB")
Fixes: b77f66002812 ("examples/pipeline: add new example application")
Fixes: edbed86d1cc3 ("examples/vdpa: introduce a new sample for vDPA")
Fixes: c19beb3f38cd ("examples/vhost_blk: introduce vhost storage sample")
Fixes: f5188211c721 ("examples/vhost_crypto: add sample application")
Cc: stable@dpdk.org
Signed-off-by: Chengchang Tang <tangchengchang@huawei.com>