crypto: s5p-sss - use the new scatterwalk functions

s5p_sg_copy_buf() open-coded a copy from/to a scatterlist using
scatterwalk_* functions that are planned for removal.  Replace it with
the new functions memcpy_from_sglist() and memcpy_to_sglist() instead.
Also take the opportunity to replace calls to scatterwalk_map_and_copy()
in the same file; this eliminates the confusing 'out' argument.

Cc: Krzysztof Kozlowski <krzk@kernel.org>
Cc: Vladimir Zapolskiy <vz@mleia.com>
Cc: linux-samsung-soc@vger.kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>