Initial commit for Planck PCB Rev 1.

- Backlight on PB7 controlled by Timer1 Fast PWM (no interrupts).
- Backlight commands connected temporarily to top left keys.
- Backlight init called from matrix.c, since there's no generic keyboard_init() override function.

keyboard/planck/led.c

@@ -22,13 +22,17 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 void led_set(uint8_t usb_led)
 {
-    // if (usb_led & (1<<USB_LED_FUNCTION)) {
-    //     // Output high.
-    //     DDRF |= (1<<0);
-    //     PORTF |= (1<<0);
-    // } else {
-    //     // Output low.
-    //     DDRF &= ~(1<<0);
-    //     PORTF &= ~(1<<0);
-    // }
+	// Using PE6 Caps Lock LED
+	if (usb_led & (1<<USB_LED_CAPS_LOCK))
+    {
+        // Output high.
+        DDRE |= (1<<6);
+        PORTE |= (1<<6);
+    }
+    else
+    {
+        // Output low.
+        DDRE &= ~(1<<6);
+        PORTE &= ~(1<<6);
+    }
 }