Remove the zeroization of a pointer variable in the AES block
functions. The code was valid but spurious and misleading since it
looked like a mistaken attempt to zeroize the pointed-to buffer.
Reported by Antonio de la Piedra, CEA Leti, France.
Note that we do not zeroize the buffer here because these are the
round keys, and they need to stay until all the blocks are processed.
They will be zeroized in mbedtls_aes_free().
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
