aesni_gcm: add driver for AES-GCM crypto operations

aesni_gcm: add driver for AES-GCM crypto operations

This patch provides the implementation of an AES-NI accelerated crypto PMD
which is dependent on Intel's multi-buffer library, see the white paper
"Fast Multi-buffer IPsec Implementations on Intel®  Architecture  Processors"

This PMD supports AES_GCM authenticated encryption and authenticated
decryption using 128-bit AES keys

The patch also contains the related unit tests functions

Signed-off-by: Declan Doherty <declan.doherty@intel.com>
Signed-off-by: Pablo de Lara <pablo.de.lara.guarch@intel.com>
Acked-by: John Griffin <john.griffin@intel.com>