sandbox, test: change hog gpio

Since commit 9ba84329 ("sandbox, test: add test for GPIO_HOG
function"), the gpio_a 0,1,2 and 3 are used by hog in test.dts.
But 2 leds 'sandbox:red' and 'sandbox:green' are using gpio_a 0
and 1. As hog always request his gpios, the led command on both
led is broken:

=> led sandbox:red
LED 'sandbox:red' not found (err=-16)

The gpio is already requested by hog, so it can't be enabled
for led 'sandbox:red'.

This commit change the gpio used by hog to 10, 11, 12 and 13,
so the led command could be used again with 'sandbox:red' and
'sandbox:green'.

Signed-off-by: Philippe Reynes <philippe.reynes@softathome.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Heiko Schocher <hs@denx.de>