added touchpad demo

demos/touchpad/main.c

@@ -0,0 +1,26 @@
+#include "ch.h"
+#include "hal.h"
+#include "gdisp.h"
+#include "touchpad.h"
+
+TOUCHPADDriver TOUCHPADD1 = {
+	&SPID1,
+};
+
+int main(void) {
+	halInit();
+	chSysInit();
+
+	gdispInit();
+	gdispClear(Lime);
+
+	tpInit(&TOUCHPADD1);
+	tpCalibrate();
+
+	gdispClear(Lime);	
+
+	while (TRUE) {
+		gdispDrawFillCircle(tpReadX(), tpReadY(), 3, Black);
+	}
+}
+