nanostack: fix inclusion of kvstore

Protect kvstore headers as well as they should not be included if kvstore is not enabled
in nanostack file system.

Author: 0xc0170

connectivity/nanostack/nanostack-hal-mbed-cmsis-rtos/ns_file_system_api.cpp

@@ -18,9 +18,9 @@
 #include <new>
 #include <string.h>
 #include "mbed_error.h"
+#if MBED_CONF_NANOSTACK_HAL_USE_KVSTORE == 1
 #include "kvstore_global_api.h"
 #include "kv_config.h"
-#if MBED_CONF_NANOSTACK_HAL_USE_KVSTORE == 1
 #include "ns_file_system.h"
 #endif