powerpc/4xx: Add PowerPC 4xx GPIO driver

This patch adds support for the GPIO functions of PPC40x and PPC44x
SOCs.

Signed-off-by: Steve Falco <sfalco@harris.com>
Acked-by: Stefan Roese <sr@denx.de>
Acked-by: Sean MacLennan <smaclennan@pikatech.com>
Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>

arch/powerpc/platforms/40x/Kconfig

@@ -169,6 +169,14 @@ config STB03xxx
 	select IBM405_ERR77
 	select IBM405_ERR51
 
+config PPC4xx_GPIO
+	bool "PPC4xx GPIO support"
+	depends on 40x
+	select ARCH_REQUIRE_GPIOLIB
+	select GENERIC_GPIO
+	help
+	  Enable gpiolib support for ppc40x based boards
+
 # 40x errata/workaround config symbols, selected by the CPU models above
 
 # All 405-based cores up until the 405GPR and 405EP have this errata.