scripts: trace_usb_capture: Clean up on exit

When the user presses Ctrl+c to exit the infinite capturing loop, ensure
that the cleanup funciton is always executed.

Signed-off-by: Carles Cufi <carles.cufi@nordicsemi.no>

Author: carlescufi

scripts/tracing/trace_capture_usb.py

@@ -86,18 +86,18 @@ def main():
     buff = usb.util.create_buffer(8192)
     read_endpoint.read(buff, 10000)
 
-    with open(output_file, "wb") as file_desc:
-        while True:
-            buff = usb.util.create_buffer(8192)
-            length = read_endpoint.read(buff, 100000)
-            for index in range(length):
-                file_desc.write(chr(buff[index]).encode('latin1'))
-
-    usb.util.release_interface(usb_device, interface)
-
-if __name__=="__main__":
     try:
-        main()
+        with open(output_file, "wb") as file_desc:
+            while True:
+                buff = usb.util.create_buffer(8192)
+                length = read_endpoint.read(buff, 100000)
+                for index in range(length):
+                    file_desc.write(chr(buff[index]).encode('latin1'))
     except KeyboardInterrupt:
+        pass
+    finally:
         print('Data capture interrupted, data saved into {}'.format(args.output))
-        sys.exit(0)
+        usb.util.release_interface(usb_device, interface)
+
+if __name__=="__main__":
+    main()