ARM: shmobile: armadillo800eva: Use keyboard as gpio-keys node name

This appears to be the best match for ePAPR.
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

arch/arm/boot/dts/r8a7740-armadillo800eva.dts

@@ -78,7 +78,7 @@ reg_5p0v: regulator@3 {
 		regulator-boot-on;
 	};
 
-	gpio-keys {
+	keyboard {
 		compatible = "gpio-keys";
 
 		power-key {