Revert "ASoC: cros_ec_codec: use crypto_shash_tfm_digest()"

This reverts commit 85fc78b8 as
a different fix has already been applied in the sound-asoc tree
and this patch is no longer required.

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Reported-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>