Add M997 support for SKR PRO 1.1 (#15394)

Marlin/src/HAL/HAL_STM32/HAL.cpp

@@ -112,4 +112,9 @@ uint16_t HAL_adc_get_result() {
   return HAL_adc_result;
 }
 
+void flashFirmware(int16_t value) {
+  UNUSED(value);
+  NVIC_SystemReset();
+}
+
 #endif // ARDUINO_ARCH_STM32 && !STM32GENERIC

Marlin/src/HAL/HAL_STM32/HAL.h

@@ -198,3 +198,6 @@ uint16_t HAL_adc_get_result();
 #define GET_PIN_MAP_PIN(index) index
 #define GET_PIN_MAP_INDEX(pin) pin
 #define PARSED_PIN_INDEX(code, dval) parser.intval(code, dval)
+
+#define PLATFORM_M997_SUPPORT
+void flashFirmware(int16_t value);