mk: added rcS_no_microSD

for boards without a microSD or USB card

mk/PX4/ROMFS/init.d/rcS_no_microSD

@@ -0,0 +1,16 @@
+#!nsh
+set USB autoconnect
+set NSH_ERROR_UART1 /dev/ttyACM0
+set NSH_ERROR_UART2 /dev/ttyS0
+
+tone_alarm /etc/tones/startup
+
+if sercon
+then
+    echo "[init] USB interface connected"
+else
+    echo "[init] No USB connected"
+fi
+
+echo Running rc.APM
+sh /etc/init.d/rc.APM