crypto: ecdsa - Fix the public key format description

Public key blob is not just x and y concatenated. It follows RFC5480
section 2.2. Address this by re-documenting the function with the
correct description of the format.

Link: https://datatracker.ietf.org/doc/html/rfc5480
Fixes: 4e660291 ("crypto: ecdsa - Add support for ECDSA signature verification")
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto/ecdsa.c

@@ -215,9 +215,8 @@ static int ecdsa_ecc_ctx_reset(struct ecc_ctx *ctx)
 }
 
 /*
- * Set the public key given the raw uncompressed key data from an X509
- * certificate. The key data contain the concatenated X and Y coordinates of
- * the public key.
+ * Set the public ECC key as defined by RFC5480 section 2.2 "Subject Public
+ * Key". Only the uncompressed format is supported.
  */
 static int ecdsa_set_pub_key(struct crypto_akcipher *tfm, const void *key, unsigned int keylen)
 {