crypto: cbc - Remove VLA usage

In the quest to remove all stack VLA usage from the kernel[1], this
uses the upper bounds on blocksize. Since this is always a cipher
blocksize, use the existing cipher max blocksize.

[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com



Change-Id: Icd5510d1b12860ffcf91f3c981a7b87515c83c34
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Git-Repo: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


Git-Commit: d73d67fbcb94409e0a92952750f162d4eb696e96
Signed-off-by: Rishabh Bhatnagar <rishabhb@codeaurora.org>