crypto: caam - Convert GCM to new AEAD interface

This patch converts the caam GCM implementations to the new AEAD
interface.  This is compile-tested only.

Note that all IV generation for GCM algorithms have been removed.
The reason is that the current generation uses purely random IVs
which is not appropriate for counter-based algorithms where we
first and foremost require uniqueness.

Of course there is no reason why you couldn't implement seqiv or
seqniv within caam since all they do is xor the sequence number
with a salt, but since I can't test this on actual hardware I'll
leave it alone for now.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>