crypto: x86/aegis - Fix sleeping when disallowed on PREEMPT_RT

crypto: x86/aegis - Fix sleeping when disallowed on PREEMPT_RT

skcipher_walk_done() can call kfree(), which takes a spinlock, which
makes it incorrect to call while preemption is disabled on PREEMPT_RT.
Therefore, end the kernel-mode FPU section before calling
skcipher_walk_done(), and restart it afterwards.

Moreover, pass atomic=false to skcipher_walk_aead_encrypt() instead of
atomic=true.  The point of atomic=true was to make skcipher_walk_done()
safe to call while in a kernel-mode FPU section, but that does not
actually work.  So just use the usual atomic=false.

Fixes: 1d373d4e8e15 ("crypto: x86 - Add optimized AEGIS implementations")
Cc: stable@vger.kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>