cores: Fix a compile error caused by streams.h update

Fix a compile error caused by the following change in nuttx.
c++ compatibility: rename reserved c++ keywords 'public' and 'this'

refs #16438

Arduino15/packages/SPRESENSE/hardware/spresense/1.0.0/cores/spresense/multi_print.c

@@ -117,7 +117,7 @@ int sync_printf(const char *fmt, ...)
   lib_memoutstream(&memoutstream, buf, sizeof(buf));
 
   va_start(ap, fmt);
-  n = lib_vsprintf((FAR struct lib_outstream_s *)&memoutstream.public, fmt, ap);
+  n = lib_vsprintf((FAR struct lib_outstream_s *)&memoutstream.common, fmt, ap);
   va_end(ap);
 
   uart_syncwrite(buf, n);