dts: bindings: gpio: arduino-mkr-header: Correct wrong D9/SCK pin number

D9/SCK pin is zephyrproject-rtos#9 pin, not #0.

Signed-off-by: TOKITA Hiroshi <[email protected]>

Author: soburi

dts/bindings/gpio/arduino-mkr-header.yaml

@@ -28,7 +28,7 @@ description: |
         21 A6/D21               D12/SCL  12
         0  D0                   D11/SDA  11
         1  D1                   D10/CPIO 10
-        2  D2                   D9/SCK   0
+        2  D2                   D9/SCK   9
         3  D3                   D8/COPI  8
         4  D4                   D7       7
         5  D5                   D6       6