System76 common board directory (#53)

* Move configuration for battery into board.mk

* lemp9: remove tcpm code

* Move touchpad to its own module

* Add kbled_reset to all platforms, move items to run on CPU reset to a function

* Add defines for battery and charger address

* Add I2C_0 export to it5570e

* Move common system76 board functions into src/board/system76/common

src/board/system76/common/ps2.c

@@ -0,0 +1,7 @@
+#include <board/ps2.h>
+
+void ps2_init(void) {
+    ps2_reset(&PS2_1);
+    ps2_reset(&PS2_2);
+    ps2_reset(&PS2_3);
+}