porting/nuttx/example: perform initialization if not done by NSH

For example, when Nimble NuttX example is the entry point for users applications.

porting/examples/nuttx/main.c

@@ -24,6 +24,9 @@
 #include <stdio.h>
 #include <pthread.h>
 #include <unistd.h>
+#include <sys/boardctl.h>
+
+#include "netutils/netinit.h"
 
 #include "nimble/nimble_npl.h"
 #include "nimble/nimble_port.h"
@@ -71,6 +74,18 @@ int main(int argc, char *argv[])
         ble_hci_sock_set_device(atoi(argv[1]));
     }
 
+#ifndef CONFIG_NSH_ARCHINIT
+    /* Perform architecture-specific initialization */
+
+    boardctl(BOARDIOC_INIT, 0);
+#endif
+
+#ifndef CONFIG_NSH_NETINIT
+    /* Bring up the network */
+
+    netinit_bringup();
+#endif
+
     printf("port init\n");
     nimble_port_init();