BACKPORT: crypto: zstd - Add zstd support

Adds zstd support to crypto and scompress. Only supports the default
level.

Previously we held off on this patch, since there weren't any users.
Now zram is ready for zstd support, but depends on CONFIG_CRYPTO_ZSTD,
which isn't defined until this patch is in. I also see a patch adding
zstd to pstore [0], which depends on crypto zstd.

[0] lkml.kernel.org/r/9c9416b2dff19f05fb4c35879aaa83d11ff72c92.1521626182.git.geliangtang@gmail.com

Signed-off-by: Nick Terrell <terrelln@fb.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

(cherry picked from commit d28fc3dbe1918333730d62aa5f0d84b6fb4e7254)
Signed-off-by: Peter Kalauskas <peskal@google.com>
Bug: 112488418
Change-Id: If8e03c1bcd2b1d66cab9230e40c7a6c2c9ecb057