event/dlb2: fix CQ depth override credit deadlock

event/dlb2: fix CQ depth override credit deadlock

This commit fixes a bug, where we could encounter a credit
deadlock due to changing the CQ depth. To remedy this situation,
the commit reduces the maximum CQ depth from 1024 to 128,
and also allows configuring the maximum enqueue depth. Maximum
enqueue depth must be tuned to the CQ depth, if the CQ depth
is increased.

Fixes: 86fe66d45667 ("event/dlb2: allow CQ depths up to 1024")
Cc: stable@dpdk.org
Signed-off-by: Timothy McDaniel <timothy.mcdaniel@intel.com>