net/iavf: fix crash in AVX512

net/iavf: fix crash in AVX512

Fix segment fault when failing to get the memory from the pool.
If there's no memory in the default cache, fall back to the
previous process.

The previous AVX2 rearm function is changed to add some AVX512
instructions and changed to a callee of the AVX2 and AVX512
rearm functions.

Fixes: 31737f2b66fb ("net/iavf: enable AVX512 for legacy Rx")
Cc: stable@dpdk.org
Reported-by: David Coyle <david.coyle@intel.com>
Signed-off-by: Wenzhuo Lu <wenzhuo.lu@intel.com>
Tested-by: David Coyle <david.coyle@intel.com>