Fix L<EVP_MD_CTX_set_pkey_ctx> links

Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/10420)

(cherry picked from commit ca7c982821cd6d7546f92623da61a6f43ee32d0a)

doc/man3/EVP_DigestSignInit.pod

@@ -57,7 +57,7 @@ The digest I<mdname> may be NULL if the signing algorithm supports it. The
 I<props> argument can always be NULL.
 
 No B<EVP_PKEY_CTX> will be created by EVP_DigestSignInit_ex() if the passed
-I<ctx> has already been assigned one via L<EVP_MD_CTX_set_ctx(3)>. See also
+I<ctx> has already been assigned one via L<EVP_MD_CTX_set_pkey_ctx(3)>. See also
 L<SM2(7)>.
 
 Only EVP_PKEY types that support signing can be used with these functions. This

doc/man3/EVP_DigestVerifyInit.pod

@@ -56,7 +56,7 @@ means the EVP_PKEY_CTX is created inside EVP_DigestVerifyInit_ex() and it will
 be freed automatically when the EVP_MD_CTX is freed).
 
 No B<EVP_PKEY_CTX> will be created by EVP_DigestSignInit_ex() if the passed
-B<ctx> has already been assigned one via L<EVP_MD_CTX_set_ctx(3)>. See also
+B<ctx> has already been assigned one via L<EVP_MD_CTX_set_pkey_ctx(3)>. See also
 L<SM2(7)>.
 
 Not all digests can be used for all key types. The following combinations apply.