Rename unnamespaced identifiers

Rename the enum constants TLS12_PRF_xxx, which are declared in a
public header but not intended for use in application code, to start
with MBEDTLS_PSA_.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/include/psa/crypto_struct.h b/include/psa/crypto_struct.h
index 6a018e1..04ece6d 100644
--- a/include/psa/crypto_struct.h
+++ b/include/psa/crypto_struct.h
@@ -228,11 +228,11 @@
 #if defined(MBEDTLS_MD_C)
 typedef enum
 {
-    TLS12_PRF_STATE_INIT,       /* no input provided */
-    TLS12_PRF_STATE_SEED_SET,   /* seed has been set */
-    TLS12_PRF_STATE_KEY_SET,    /* key has been set */
-    TLS12_PRF_STATE_LABEL_SET,  /* label has been set */
-    TLS12_PRF_STATE_OUTPUT      /* output has been started */
+    PSA_TLS12_PRF_STATE_INIT,       /* no input provided */
+    PSA_TLS12_PRF_STATE_SEED_SET,   /* seed has been set */
+    PSA_TLS12_PRF_STATE_KEY_SET,    /* key has been set */
+    PSA_TLS12_PRF_STATE_LABEL_SET,  /* label has been set */
+    PSA_TLS12_PRF_STATE_OUTPUT      /* output has been started */
 } psa_tls12_prf_key_derivation_state_t;
 
 typedef struct psa_tls12_prf_key_derivation_s