event/dlb2: support CQ weight

event/dlb2: support CQ weight

Enabling the weight limit on a CQ allows the enqueued QEs' 2-bit weight
value (representing weights of 1, 2, 4, and 8) to factor into whether a
CQ is full. If the sum of the weights of the QEs in the CQ meet or exceed
its weight limit, DLB will stop scheduling QEs to it (until software pops
enough QEs from the CQ to reverse that).

CQ weight support is enabled via the command line, and applies to
DLB 2.5 (and above) load balanced ports. The DLB2 documentation will
be updated with further details.

Signed-off-by: Timothy McDaniel <timothy.mcdaniel@intel.com>