crypto: x86/cast6-avx - remove LRW algorithm

The LRW template now wraps an ECB mode algorithm rather than the block
cipher directly.  Therefore it is now redundant for crypto modules to
wrap their ECB code with generic LRW code themselves via lrw_crypt().

Remove the lrw-cast6-avx algorithm which did this.  Users who request
lrw(cast6) and previously would have gotten lrw-cast6-avx will now get
lrw(ecb-cast6-avx) instead, which is just as fast.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>