Add missing bracket for CPP guard

Signed-off-by: Steven Cooreman <steven.cooreman@silabs.com>
diff --git a/library/psa_crypto_its.h b/library/psa_crypto_its.h
index 93c4ce9..b671d63 100644
--- a/library/psa_crypto_its.h
+++ b/library/psa_crypto_its.h
@@ -142,4 +142,8 @@
  */
 psa_status_t psa_its_remove(psa_storage_uid_t uid);
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif /* PSA_CRYPTO_ITS_H */