crypto: algif_aead - fix uninitialized ctx->init

In skcipher_accept_parent_nokey() the whole af_alg_ctx structure is
cleared by memset() after allocation, so add such memset() also to
aead_accept_parent_nokey() so that the new "init" field is also
initialized to zero. Without that the initial ctx->init checks might
randomly return true and cause errors.

While there, also remove the redundant zero assignments in both
functions.

Found via libkcapi testsuite.

Cc: Stephan Mueller <smueller@chronox.de>
Fixes: f3c802a1 ("crypto: algif_aead - Only wake up when ctx->more is zero")
Suggested-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>