eventdev: update references to removed function

eventdev: update references to removed function

Remove references to the (deleted) rte_event_port_enqueue_depth()
function in the Doxygen comments for rte_event_enqueue_burst() and
friends, and replace with references to rte_event_port_attr_get().

Fixes: 78ffab961155 ("eventdev: add port attribute function")
Fixes: c9bf83947e2e ("eventdev: add eth Tx adapter APIs")
Cc: stable@dpdk.org
Signed-off-by: Erik Gabriel Carrillo <erik.g.carrillo@intel.com>
Acked-by: Jerin Jacob <jerinj@marvell.com>
Acked-by: John McNamara <john.mcnamara@intel.com>