alif: Support running the port on the HE core.

The same MicroPython firmware is built for the HE but with slightly
different options, for example no USB.

Signed-off-by: iabdalkader <i.abdalkader@gmail.com>

ports/alif/modules/he/_boot.py

@@ -0,0 +1,21 @@
+import openamp
+import time
+from machine import Pin
+
+
+def ept_recv_callback(src_addr, data):
+    print("Received message on endpoint", data)
+
+
+# Create a new RPMsg endpoint to communicate with main core.
+ept = openamp.Endpoint("vuart-channel", callback=ept_recv_callback)
+
+pin = Pin("LED_BLUE", Pin.OUT)
+
+count = 0
+while True:
+    if ept.is_ready():
+        ept.send("Hello from HE %d" % count, timeout=1000)
+        count += 1
+    time.sleep_ms(100)
+    pin(not pin())