crypto: artpec6 - set correct iv size for gcm(aes)

[ Upstream commit 6d6e71feb183aa588c849e20e7baa47cb162928a ]

The IV size should not include the 32 bit counter. Because we had the
IV size set as 16 the transform only worked when the IV input was zero
padded.

Fixes: a21eb94f ("crypto: axis - add ARTPEC-6/7 crypto accelerator driver")
Signed-off-by: Lars Persson <larper@axis.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>