stmhal: Set STM32F7DISC CPU Frequency to 216 MHz

This set the CPU frequency to 216 MHz (the max) and
leaves the USB Frequency at 48 MHz.

These settings were copied from one of the HAL examples.

stmhal/boards/STM32F7DISC/mpconfigboard.h

@@ -20,12 +20,19 @@
 void STM32F7DISC_board_early_init(void);
 
 // HSE is 25MHz
+// VCOClock = HSE * PLLN / PLLM = 25 MHz * 432 / 25 = 432 MHz
+// SYSCLK = VCOClock / PLLP = 432 MHz / 2 = 216 MHz
+// USB/SDMMC/RNG Clock = VCOClock / PLLQ = 432 MHz / 9 = 48 MHz
 #define MICROPY_HW_CLK_PLLM (25)
-#define MICROPY_HW_CLK_PLLN (336)
+#define MICROPY_HW_CLK_PLLN (432)
 #define MICROPY_HW_CLK_PLLP (RCC_PLLP_DIV2)
-#define MICROPY_HW_CLK_PLLQ (7)
+#define MICROPY_HW_CLK_PLLQ (9)
 
-#define MICROPY_HW_FLASH_LATENCY    FLASH_LATENCY_6
+// From the reference manual, for 2.7V to 3.6V
+// 151-180 MHz => 5 wait states
+// 181-210 MHz => 6 wait states
+// 211-216 MHz => 7 wait states
+#define MICROPY_HW_FLASH_LATENCY    FLASH_LATENCY_7 // 210-216 MHz needs 7 wait states
 
 // UART config
 #define MICROPY_HW_UART1_TX_PORT    (GPIOA)