Move M250 to cpp

Marlin/src/gcode/lcd/M250.cpp

@@ -20,12 +20,21 @@
  *
  */
 
+#include "../../inc/MarlinConfig.h"
+
+#if HAS_LCD_CONTRAST
+
+#include "../gcode.h"
+#include "../../lcd/ultralcd.h"
+
 /**
  * M250: Read and optionally set the LCD contrast
  */
-void gcode_M250() {
+void GcodeSuite::M250() {
   if (parser.seen('C')) set_lcd_contrast(parser.value_int());
   SERIAL_PROTOCOLPGM("lcd contrast value: ");
   SERIAL_PROTOCOL(lcd_contrast);
   SERIAL_EOL();
 }
+
+#endif // HAS_LCD_CONTRAST