tests: drivers: gpio-async: Add overlay for tiny2040

Add an overlay to configure the gpio used.  Currently, this is set as an
"LED" even though this is not correct, as Zephyr doesn't have any DT
entries for general purpose GPIOs.  Key matrix might make sense, if the
Zephyr driver can be kept from claiming it.

Signed-off-by: David Brown <[email protected]>

Author: d3zd3z

tests/drivers/gpio-async/boards/pimoroni_tiny_2040.overlay

@@ -0,0 +1,13 @@
+/ {
+	gpio-leds {
+		compatible = "gpio-leds";
+		col0: col0 {
+			gpios = <&gpio0 6 GPIO_ACTIVE_HIGH>;
+			label = "Column 0";
+		};
+		row0: row0 {
+			gpios = <&gpio0 0 (GPIO_PULL_DOWN | GPIO_ACTIVE_HIGH)>;
+			label = "Row 0";
+		};
+	};
+};