Fix ChibiOS to version 21.11.2

Makefile

@@ -89,7 +89,7 @@ PROJECT = acc-tst
 MCU  = cortex-m3
 
 # Imported source files and paths.
-CHIBIOS  := C:/MCU/ChibiOS
+CHIBIOS  := C:/MCU/ChibiOS_21.11.2
 CONFDIR  := ./cfg
 BUILDDIR := ./build
 DEPDIR   := ./.dep