Align names to use "opaque" only everywhere

It's better for names in the API to describe the "what" (opaque keys) rather
than the "how" (using PSA), at least since we don't intend to have multiple
function doing the same "what" in different ways in the foreseeable future.
diff --git a/include/mbedtls/pk.h b/include/mbedtls/pk.h
index 3f64093..001dcca 100644
--- a/include/mbedtls/pk.h
+++ b/include/mbedtls/pk.h
@@ -87,7 +87,7 @@
     MBEDTLS_PK_ECDSA,
     MBEDTLS_PK_RSA_ALT,
     MBEDTLS_PK_RSASSA_PSS,
-    MBEDTLS_PK_OPAQUE_PSA,
+    MBEDTLS_PK_OPAQUE,
 } mbedtls_pk_type_t;
 
 /**
@@ -210,7 +210,7 @@
  * \brief           Free a mbedtls_pk_context
  *
  * \note            For contexts that have been set up with
- *                  mbedtls_pk_setup_psa(), this does not free the underlying
+ *                  mbedtls_pk_setup_opaque(), this does not free the underlying
  *                  key slot and you still need to call psa_destroy_key()
  *                  independently if you want to destroy that key.
  */
@@ -271,7 +271,7 @@
  * \note            This function is currently only available for ECC keypair.
  *                  Support for other key types will be added later.
  */
-int mbedtls_pk_setup_psa( mbedtls_pk_context *ctx, const psa_key_slot_t key );
+int mbedtls_pk_setup_opaque( mbedtls_pk_context *ctx, const psa_key_slot_t key );
 #endif /* MBEDTLS_USE_PSA_CRYPTO */
 
 #if defined(MBEDTLS_PK_RSA_ALT_SUPPORT)
diff --git a/include/mbedtls/pk_internal.h b/include/mbedtls/pk_internal.h
index 7288e9b..fc9ba13 100644
--- a/include/mbedtls/pk_internal.h
+++ b/include/mbedtls/pk_internal.h
@@ -136,7 +136,7 @@
 #endif
 
 #if defined(MBEDTLS_USE_PSA_CRYPTO)
-extern const mbedtls_pk_info_t mbedtls_pk_opaque_psa_info;
+extern const mbedtls_pk_info_t mbedtls_pk_opaque_info;
 #endif
 
 #endif /* MBEDTLS_PK_WRAP_H */