net/ixgbe: fix received packets number for ARM

net/ixgbe: fix received packets number for ARM

To get better performance, Rx bulk alloc recv function will scan 8 descs
in one time, but the statuses are not consistent on ARM platform because
the memory allocated for Rx descriptors is cacheable hugepages.
This patch is to calculate the number of received packets by scan DD bit
sequentially, and stops when meeting the first packet with DD bit unset.

Fixes: 7431041062b9 ("ixgbe: allow rx bulk alloc")
Cc: stable@dpdk.org
Signed-off-by: Jianbo Liu <jianbo.liu@linaro.org>
Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>