crypto: testmgr - make extra tests depend on cryptomgr

The crypto self-tests are part of the "cryptomgr" module, which can
technically be disabled (though it rarely is).  If you do so, currently
you can still enable CRYPTO_MANAGER_EXTRA_TESTS, which doesn't make
sense since in that case testmgr.c isn't compiled at all.  Fix it by
making it CRYPTO_MANAGER_EXTRA_TESTS depend on CRYPTO_MANAGER2, like
CRYPTO_MANAGER_DISABLE_TESTS already does.

Fixes: 5b2706a4 ("crypto: testmgr - introduce CONFIG_CRYPTO_MANAGER_EXTRA_TESTS")
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>