crypto: aesni - add wrapper for generic gcm(aes)

When I added generic-gcm-aes I didn't add a wrapper like the one
provided for rfc4106(gcm(aes)). We need to add a cryptd wrapper to fall
back on in case the FPU is not available, otherwise we might corrupt the
FPU state.

Fixes: cce2ea8d

 ("crypto: aesni - add generic gcm(aes)")
Cc: <stable@vger.kernel.org>
Reported-by: Ilya Lesokhin <ilyal@mellanox.com>
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Reviewed-by: Stefano Brivio <sbrivio@redhat.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>