Fix CHITU_F103 pio.board name (#18486)

platformio.ini

@@ -672,7 +672,7 @@ lib_ignore  = LiquidCrystal, LiquidTWI2, Adafruit NeoPixel, TMCStepper, U8glib-H
 [env:chitu_f103]
 platform      = ${common_stm32f1.platform}
 extends       = common_stm32f1
-board         = chitu_f103
+board         = CHITU_F103
 extra_scripts = pre:buildroot/share/PlatformIO/scripts/STM32F1_create_variant.py
   buildroot/share/PlatformIO/scripts/chitu_crypt.py
 build_flags   = ${common_stm32f1.build_flags}