stm32/boards/NUCLEO_L432KC: Disable complex nos and default frozen mods.

To save space, since this board only hase 256k of flash.

ports/stm32/boards/NUCLEO_L432KC/mpconfigboard.h

@@ -3,6 +3,7 @@
 
 #define MICROPY_EMIT_THUMB          (0)
 #define MICROPY_EMIT_INLINE_THUMB   (0)
+#define MICROPY_PY_BUILTINS_COMPLEX (0)
 #define MICROPY_PY_USOCKET          (0)
 #define MICROPY_PY_NETWORK          (0)
 #define MICROPY_PY_STM              (0)

ports/stm32/boards/NUCLEO_L432KC/mpconfigboard.mk

@@ -3,3 +3,6 @@ CMSIS_MCU = STM32L432xx
 AF_FILE = boards/stm32l432_af.csv
 LD_FILES = boards/stm32l432.ld boards/common_basic.ld
 OPENOCD_CONFIG = boards/openocd_stm32l4.cfg
+
+# Don't include default frozen modules because MCU is tight on flash space
+FROZEN_MPY_DIR ?=