[CRYPTO] aes: Fixed array boundary violation

The AES setkey routine writes 64 bytes to the E_KEY area even though
there are only 60 bytes there.  It is in fact safe since E_KEY is
immediately follwed by D_KEY which is initialised afterwards.  However,
doing this may trigger undefined behaviour and makes Coverity unhappy.

So by combining E_KEY and D_KEY into one array we sidestep this issue
altogether.

This problem was reported by Adrian Bunk.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>