Provide some missing Arduino macros (#16497)

Marlin/src/feature/dac/dac_mcp4728.h

@@ -29,6 +29,24 @@
 
 #include <Wire.h>
 
+/**
+ * The following three macros are only used in this piece of code related to mcp4728.
+ * They are defined in the standard Arduino framework but could be undefined in 32 bits Arduino frameworks.
+ * (For instance not defined in Arduino lpc176x framework)
+ * So we have to define them if needed.
+ */
+#ifndef word
+  #define word(h, l)  ((uint8_t) ((h << 8) | l))
+#endif
+
+#ifndef lowByte
+  #define lowByte(w)  ((uint8_t) ((w) & 0xff))
+#endif
+
+#ifndef highByte
+  #define highByte(w) ((uint8_t) ((w) >> 8))
+#endif
+
 #define defaultVDD     DAC_STEPPER_MAX //was 5000 but differs with internal Vref
 #define BASE_ADDR      0x60
 #define RESET          0b00000110