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/include/linux/platform_data/macb.h b/include/linux/platform_data/macb.h
index e7c748f..b081c72 100644
--- a/include/linux/platform_data/macb.h
+++ b/include/linux/platform_data/macb.h
@@ -10,7 +10,7 @@
 
 struct macb_platform_data {
 	u32		phy_mask;
-	u8		phy_irq_pin;	/* PHY IRQ */
+	int		phy_irq_pin;	/* PHY IRQ */
 	u8		is_rmii;	/* using RMII interface? */
 };