stm32/boards/STM32F429DISC: Add burst len and autorefresh to SDRAM cfg.
To align with recent changes to sdram.c.
#define MICROPY_HW_SDRAM_TIMING_TRCD (2)
#define MICROPY_HW_SDRAM_REFRESH_RATE (64) // ms
+#define MICROPY_HW_SDRAM_BURST_LENGTH 2
#define MICROPY_HW_SDRAM_CAS_LATENCY 3
#define MICROPY_HW_SDRAM_COLUMN_BITS_NUM 8
#define MICROPY_HW_SDRAM_ROW_BITS_NUM 12
#define MICROPY_HW_SDRAM_RPIPE_DELAY 1
#define MICROPY_HW_SDRAM_RBURST (0)
#define MICROPY_HW_SDRAM_WRITE_PROTECTION (0)
+#define MICROPY_HW_SDRAM_AUTOREFRESH_NUM (4)
#define MICROPY_HW_FMC_SDCKE1 (pin_B5)
#define MICROPY_HW_FMC_SDNE1 (pin_B6)
