ARM: at91/boards: use -EINVAL for invalid gpio

this will allow to use gpio_is_valid

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Cc: Nicolas Ferre <nicolas.ferre@atmel.com>
diff --git a/arch/arm/mach-at91/board-pcontrol-g20.c b/arch/arm/mach-at91/board-pcontrol-g20.c
index 9a6e021..b4a12fc 100644
--- a/arch/arm/mach-at91/board-pcontrol-g20.c
+++ b/arch/arm/mach-at91/board-pcontrol-g20.c
@@ -107,6 +107,8 @@
  */
 static struct at91_usbh_data __initdata usbh_data = {
 	.ports		= 2,
+	.vbus_pin	= {-EINVAL, -EINVAL},
+	.overcurrent_pin= {-EINVAL, -EINVAL},
 };