meter: provide experimental alias for matured API

meter: provide experimental alias for matured API

On v20.02 some meter APIs have been matured and symbols moved from
EXPERIMENTAL to DPDK_20.0.1 block.

This can break the applications that were using these mentioned APIs on
v19.11. Although there is no modification on the APIs and the action is
positive and matures the APIs, the affect can be negative to
applications.

This patch provides aliasing by duplicating the existing and versioned
symbols as experimental.

Since symbols moved from DPDK_20.0.1 to DPDK_21 block in the v20.05, the
aliasing done between EXPERIMENTAL and DPDK_21.

With DPDK_21 ABI (DPDK v20.11) all aliasing will be removed and only
stable version of the APIs will remain.

Fixes: 30512af820fe ("meter: remove experimental flag from RFC4115 trTCM API")
Cc: stable@dpdk.org
Signed-off-by: Ferruh Yigit <ferruh.yigit@intel.com>
Acked-by: Cristian Dumitrescu <cristian.dumitrescu@intel.com>
Acked-by: Ray Kinsella <mdr@ashroe.eu>