crypto: arm/crc32 - enable module autoloading based on CPU feature bits

Make the module autoloadable by tying it to the CPU feature bits that
describe whether the optional instructions it relies on are implemented
by the current CPU.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>