telemetry: fix passing full params string to command

telemetry: fix passing full params string to command

Telemetry only passed the first param to the command handler if multiple
were entered by the user, separated by commas. Telemetry is required to
pass the full params string to the command, by splitting by a comma
delimiter only once to remove the command part of the string. This will
enable future commands to take multiple param values.

Fixes: b1ad0e124536 ("rawdev: add telemetry callbacks")
Fixes: c190daedb9b1 ("ethdev: add telemetry callbacks")
Fixes: 6dd571fd07c3 ("telemetry: introduce new functionality")
Cc: stable@dpdk.org
Signed-off-by: Ciara Power <ciara.power@intel.com>
Acked-by: Bruce Richardson <bruce.richardson@intel.com>