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-rsi-ews.c b/arch/arm/mach-at91/board-rsi-ews.c
index ed3b21f..af0750f 100644
--- a/arch/arm/mach-at91/board-rsi-ews.c
+++ b/arch/arm/mach-at91/board-rsi-ews.c
@@ -70,6 +70,8 @@
  */
 static struct at91_usbh_data rsi_ews_usbh_data __initdata = {
 	.ports		= 1,
+	.vbus_pin	= {-EINVAL, -EINVAL},
+	.overcurrent_pin= {-EINVAL, -EINVAL},
 };
 
 /*