Update comments to match function parameter names

CLA: trivial
Reviewed-by: NRich Salz <rsalz@openssl.org>
Reviewed-by: NRichard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/4407)

include/openssl/bn.h

@@ -186,7 +186,7 @@ int BN_sqr(BIGNUM *r, const BIGNUM *a, BN_CTX *ctx);
  */
 void BN_set_negative(BIGNUM *b, int n);
 /** BN_is_negative returns 1 if the BIGNUM is negative
- * \param  a  pointer to the BIGNUM object
+ * \param  b  pointer to the BIGNUM object
  * \return 1 if a < 0 and 0 otherwise
  */
 int BN_is_negative(const BIGNUM *b);

include/openssl/ec.h

@@ -774,7 +774,7 @@ EC_KEY *EC_KEY_dup(const EC_KEY *src);
 int EC_KEY_up_ref(EC_KEY *key);
 
 /** Returns the ENGINE object of a EC_KEY object
- *  \param  key  EC_KEY object
+ *  \param  eckey  EC_KEY object
  *  \return the ENGINE object (possibly NULL).
  */
 ENGINE *EC_KEY_get0_engine(const EC_KEY *eckey);