crypto: x86 - convert to use crypto_simd_usable()

Replace all calls to irq_fpu_usable() in the x86 crypto code with
crypto_simd_usable(), in order to allow testing the no-SIMD code paths.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>