stm32/mboot: Enable LFS2_READONLY for mboot builds with littlefs.
To reduce code size, since mboot does not modify the filesystem.
@@ -71,7 +71,7 @@ CFLAGS += -DBOARD_$(BOARD)
CFLAGS += -DAPPLICATION_ADDR=$(TEXT0_ADDR)
CFLAGS += -DFFCONF_H=\"ports/stm32/mboot/ffconf.h\"
CFLAGS += -DLFS1_NO_MALLOC -DLFS1_NO_DEBUG -DLFS1_NO_WARN -DLFS1_NO_ERROR -DLFS1_NO_ASSERT
-CFLAGS += -DLFS2_NO_MALLOC -DLFS2_NO_DEBUG -DLFS2_NO_WARN -DLFS2_NO_ERROR -DLFS2_NO_ASSERT
+CFLAGS += -DLFS2_NO_MALLOC -DLFS2_NO_DEBUG -DLFS2_NO_WARN -DLFS2_NO_ERROR -DLFS2_NO_ASSERT -DLFS2_READONLY
CFLAGS += -DBUILDING_MBOOT=1
CFLAGS += -DMICROPY_HW_STM32WB_FLASH_SYNCRONISATION=0
CFLAGS += -DBOOTLOADER_DFU_USB_VID=$(BOOTLOADER_DFU_USB_VID) -DBOOTLOADER_DFU_USB_PID=$(BOOTLOADER_DFU_USB_PID)
