orinoco: Use shash instead of ahash for MIC calculations

Eric Biggers pointed out that the orinoco driver pointed scatterlists
at the stack.

Fix it by switching from ahash to shash.  The result should be
simpler, faster, and more correct.

Cc: stable@vger.kernel.org # 4.9 only
Reported-by: Eric Biggers <ebiggers3@gmail.com>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>