crypto: omap-aes - Add support for GCM mode

OMAP AES hw supports AES-GCM mode. This patch adds support for GCM and
RFC4106 GCM mode in omap-aes driver. The GCM implementation is mostly
written into its own source file, which gets built into the same driver
binary as the existing AES support.

Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
[t-kristo@ti.com: forward port to latest upstream kernel, conversion to use
 omap-crypto lib and some additional fixes]
Signed-off-by: Tero Kristo <t-kristo@ti.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>