crypto: ecdsa - Fix enc/dec size reported by KEYCTL_PKEY_QUERY

crypto: ecdsa - Fix enc/dec size reported by KEYCTL_PKEY_QUERY

KEYCTL_PKEY_QUERY system calls for ecdsa keys return the key size as
max_enc_size and max_dec_size, even though such keys cannot be used for
encryption/decryption.  They're exclusively for signature generation or
verification.

Only rsa keys with pkcs1 encoding can also be used for encryption or
decryption.

Return 0 instead for ecdsa keys (as well as ecrdsa keys).

Signed-off-by: Lukas Wunner <lukas@wunner.de>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Ignat Korchagin <ignat@cloudflare.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>