Correct padding mode flag name for EVP_PKEY_decrypt/encrypt() examples

The example code in EVP_PKEY_decrypt(3) and EVP_PKEY_encrypt(3) and uses
a nonexistent padding mode `RSA_OAEP_PADDING`, which should be
`RSA_PKCS1_OAEP_PADDING` instead.

CLA: trivial

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Shane Lontis <shane.lontis@oracle.com>
Reviewed-by: Paul Dale <pauli@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/18255)
diff --git a/doc/man3/EVP_PKEY_decrypt.pod b/doc/man3/EVP_PKEY_decrypt.pod
index e85541b..b624600 100644
--- a/doc/man3/EVP_PKEY_decrypt.pod
+++ b/doc/man3/EVP_PKEY_decrypt.pod
@@ -71,7 +71,7 @@
      /* Error occurred */
  if (EVP_PKEY_decrypt_init(ctx) <= 0)
      /* Error */
- if (EVP_PKEY_CTX_set_rsa_padding(ctx, RSA_OAEP_PADDING) <= 0)
+ if (EVP_PKEY_CTX_set_rsa_padding(ctx, RSA_PKCS1_OAEP_PADDING) <= 0)
      /* Error */
 
  /* Determine buffer length */
diff --git a/doc/man3/EVP_PKEY_encrypt.pod b/doc/man3/EVP_PKEY_encrypt.pod
index 9ff6ed6..c5d91e1 100644
--- a/doc/man3/EVP_PKEY_encrypt.pod
+++ b/doc/man3/EVP_PKEY_encrypt.pod
@@ -74,7 +74,7 @@
      /* Error occurred */
  if (EVP_PKEY_encrypt_init(ctx) <= 0)
      /* Error */
- if (EVP_PKEY_CTX_set_rsa_padding(ctx, RSA_OAEP_PADDING) <= 0)
+ if (EVP_PKEY_CTX_set_rsa_padding(ctx, RSA_PKCS1_OAEP_PADDING) <= 0)
      /* Error */
 
  /* Determine buffer length */