event/octeontx2: add devargs for inflight buffer count

event/octeontx2: add devargs for inflight buffer count

The number of events for a *open system* event device is specified
as -1 as per the eventdev specification.
Since, Octeontx2 SSO inflight events are only limited by DRAM size, the
xae_cnt devargs parameter is introduced to provide upper limit for
in-flight events.

Example:
	--dev "0002:0e:00.0,xae_cnt=8192"

Signed-off-by: Pavan Nikhilesh <pbhagavatula@marvell.com>
Acked-by: Jerin Jacob <jerinj@marvell.com>