ppc4xx: Move gpio.h to ppc4xx-gpio.h since its ppc4xx specific

Signed-off-by: Stefan Roese <sr@denx.de>
diff --git a/arch/powerpc/cpu/ppc4xx/cpu_init.c b/arch/powerpc/cpu/ppc4xx/cpu_init.c
index 7a7954d..6456dc7 100644
--- a/arch/powerpc/cpu/ppc4xx/cpu_init.c
+++ b/arch/powerpc/cpu/ppc4xx/cpu_init.c
@@ -25,7 +25,7 @@
 #include <watchdog.h>
 #include <asm/ppc4xx-emac.h>
 #include <asm/processor.h>
-#include <asm/gpio.h>
+#include <asm/ppc4xx-gpio.h>
 #include <asm/ppc4xx.h>
 
 #if defined(CONFIG_405GP)  || defined(CONFIG_405EP)