event/octeontx2: reduce chunk pool memory usage

event/octeontx2: reduce chunk pool memory usage

Reduce amount of memory used by chunk pool when the mempool used
is OCTEONTX2 NPA.
Previously, the number of chunks configured when NPA is used is
equal to the number of timers requested plus the number of buckets
and if the max timeout is long enough w.r.t. resolution requested
there will a large number of buckets which would cause high memory
usage.
Reduce the number of chunks when NPA is used to the number of timers
requested as buckets that are processed chunk lists are automatically
freed.

Signed-off-by: Pavan Nikhilesh <pbhagavatula@marvell.com>