arm: add host uart driver tests

All host tests currently pass
Some async refactors may not work well on device, will try later

arm/prog.py

@@ -1,6 +1,7 @@
 import serial
 import struct
 import sys
+import time
 
 offset = 0x800
 tty = 'tty'
@@ -41,11 +42,16 @@ def main():
     s = serial.Serial(tty, baud, timeout=1)
     write(s, offset, dat)
     jump(s, offset)
+    last_dat = time.time()
 
     while True:
         dat = s.read()
         if not dat:
-            break
+            if time.time() - last_dat > 1.0:
+                print('Data timeout')
+                break
+            continue
+        last_dat = time.time()
         sys.stdout.buffer.write(dat)