stm: Sort configuration options and make them all conditional

This makes them all overridable on the board level, tersely

Author: jepler

ports/stm/mpconfigport.mk

@@ -1,59 +1,56 @@
-MPY_TOOL_LONGINT_IMPL = -mlongint-impl=mpz
-LONGINT_IMPL = MPZ
-INTERNAL_LIBM = 1
-USB_SERIAL_NUMBER_LENGTH = 24
+MPY_TOOL_LONGINT_IMPL ?= -mlongint-impl=mpz
+LONGINT_IMPL ?= MPZ
+INTERNAL_LIBM ?= 1
+USB_SERIAL_NUMBER_LENGTH ?= 24
 
 ifeq ($(MCU_VARIANT),STM32F405xx)
-	CIRCUITPY_FRAMEBUFFERIO = 1
-	CIRCUITPY_RGBMATRIX = 1
+	CIRCUITPY_FRAMEBUFFERIO ?= 1
+	CIRCUITPY_RGBMATRIX ?= 1
 endif
 
 ifeq ($(MCU_SERIES),F4)
 	# Not yet implemented common-hal modules:
-	CIRCUITPY_AUDIOBUSIO = 0
-	CIRCUITPY_AUDIOIO = 0
-	CIRCUITPY_ROTARYIO = 0
-	CIRCUITPY_COUNTIO = 0
-	CIRCUITPY_RTC = 0
-	CIRCUITPY_FREQUENCYIO = 0
-	CIRCUITPY_I2CSLAVE = 0
-	# Can be overridden on board level
-	ifndef CIRCUITPY_NVM
-		CIRCUITPY_NVM = 0
-	endif
+	CIRCUITPY_AUDIOBUSIO ?= 0
+	CIRCUITPY_AUDIOIO ?= 0
+	CIRCUITPY_COUNTIO ?= 0
+	CIRCUITPY_FREQUENCYIO ?= 0
+	CIRCUITPY_I2CSLAVE ?= 0
+	CIRCUITPY_NVM ?= 0
+	CIRCUITPY_ROTARYIO ?= 0
+	CIRCUITPY_RTC ?= 0
 	CIRCUITPY_USB_MIDI ?= 0
 	CIRCUITPY_USB_HID ?= 0
 endif
 
 ifeq ($(MCU_SERIES),H7)
 	# Not yet implemented common-hal modules:
-	CIRCUITPY_ANALOGIO = 0
-	CIRCUITPY_NEOPIXEL_WRITE = 0
-	CIRCUITPY_PULSEIO = 0
-	CIRCUITPY_NVM = 0
-	CIRCUITPY_AUDIOBUSIO = 0
-	CIRCUITPY_AUDIOIO = 0
-	CIRCUITPY_COUNTIO = 0
-	CIRCUITPY_ROTARYIO = 0
-	CIRCUITPY_RTC = 0
-	CIRCUITPY_FREQUENCYIO = 0
-	CIRCUITPY_I2CSLAVE = 0
-	CIRCUITPY_USB_MIDI ?= 0
+	CIRCUITPY_ANALOGIO ?= 0
+	CIRCUITPY_AUDIOBUSIO ?= 0
+	CIRCUITPY_AUDIOIO ?= 0
+	CIRCUITPY_COUNTIO ?= 0
+	CIRCUITPY_FREQUENCYIO ?= 0
+	CIRCUITPY_I2CSLAVE ?= 0
+	CIRCUITPY_NEOPIXEL_WRITE ?= 0
+	CIRCUITPY_NVM ?= 0
+	CIRCUITPY_PULSEIO ?= 0
+	CIRCUITPY_ROTARYIO ?= 0
+	CIRCUITPY_RTC ?= 0
 	CIRCUITPY_USB_HID ?= 0
+	CIRCUITPY_USB_MIDI ?= 0
 endif
 
 ifeq ($(MCU_SERIES),F7)
 	# Not yet implemented common-hal modules:
-	CIRCUITPY_ANALOGIO = 0
-	CIRCUITPY_NEOPIXEL_WRITE = 0
-	CIRCUITPY_NVM = 0
-	CIRCUITPY_AUDIOBUSIO = 0
-	CIRCUITPY_AUDIOIO = 0
-	CIRCUITPY_ROTARYIO = 0
-	CIRCUITPY_COUNTIO = 0
-	CIRCUITPY_RTC = 0
-	CIRCUITPY_FREQUENCYIO = 0
-	CIRCUITPY_I2CSLAVE = 0
-	CIRCUITPY_USB_MIDI ?= 0
+	CIRCUITPY_ANALOGIO ?= 0
+	CIRCUITPY_AUDIOBUSIO ?= 0
+	CIRCUITPY_AUDIOIO ?= 0
+	CIRCUITPY_COUNTIO ?= 0
+	CIRCUITPY_FREQUENCYIO ?= 0
+	CIRCUITPY_I2CSLAVE ?= 0
+	CIRCUITPY_NEOPIXEL_WRITE ?= 0
+	CIRCUITPY_NVM ?= 0
+	CIRCUITPY_ROTARYIO ?= 0
+	CIRCUITPY_RTC ?= 0
 	CIRCUITPY_USB_HID ?= 0
+	CIRCUITPY_USB_MIDI ?= 0
 endif