Fix PROV_RC5_CTX's original structure name

It looks like a typo when copy & pasting the structure from blowfish.

Reviewed-by: Shane Lontis <shane.lontis@oracle.com>
Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/19186)

providers/implementations/ciphers/cipher_rc5.h

@@ -10,7 +10,7 @@
 #include <openssl/rc5.h>
 #include "prov/ciphercommon.h"
 
-typedef struct prov_blowfish_ctx_st {
+typedef struct prov_rc5_ctx_st {
     PROV_CIPHER_CTX base;      /* Must be first */
     union {
         OSSL_UNION_ALIGN;