When computing the head of CQE ring of prefetch, use qmask to point to
the correct head index on wrap around case.
Fixes: cc4d7693f2 ("net/octeontx2: support Rx")
Cc: stable@dpdk.org
Signed-off-by: Kommula Shiva Shankar <kshankar@marvell.com>
Acked-by: Jerin Jacob <jerinj@marvell.com>