Fix examples in EVP_PKEY_encapsulate/decapsulate documentation

Fixes openssl#25448

Reviewed-by: Matt Caswell <[email protected]>
Reviewed-by: Dmitry Belyavskiy <[email protected]>
Reviewed-by: Tomas Mraz <[email protected]>
(Merged from openssl#25450)

Author: Зишан Мирза

doc/man3/EVP_PKEY_decapsulate.pod

@@ -64,7 +64,7 @@ Decapsulate data using RSA:
  unsigned char *secret = NULL;;
 
  ctx = EVP_PKEY_CTX_new_from_pkey(libctx, rsa_priv_key, NULL);
- if (ctx = NULL)
+ if (ctx == NULL)
      /* Error */
  if (EVP_PKEY_decapsulate_init(ctx, NULL) <= 0)
      /* Error */

doc/man3/EVP_PKEY_encapsulate.pod

@@ -70,7 +70,7 @@ Encapsulate an RSASVE key (for RSA keys).
  unsigned char *out = NULL, *secret = NULL;
 
  ctx = EVP_PKEY_CTX_new_from_pkey(libctx, rsa_pub_key, NULL);
- if (ctx = NULL)
+ if (ctx == NULL)
      /* Error */
  if (EVP_PKEY_encapsulate_init(ctx, NULL) <= 0)
      /* Error */