crypto: skcipher - Add dependency on ecb

As lskcipher requires the ecb wrapper for the transition add an
explicit dependency on it so that it is always present.  This can
be removed once all simple ciphers have been converted to lskcipher.

Reported-by: Nathan Chancellor <nathan@kernel.org>
Fixes: 705b52fe

 ("crypto: cbc - Convert from skcipher to lskcipher")
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>