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

Signed-off-by: Stefan Roese <sr@denx.de>
diff --git a/board/quad100hd/nand.c b/board/quad100hd/nand.c
index 35525bc..a222099 100644
--- a/board/quad100hd/nand.c
+++ b/board/quad100hd/nand.c
@@ -24,7 +24,7 @@
 #include <common.h>
 #include <config.h>
 #if defined(CONFIG_CMD_NAND)
-#include <asm/gpio.h>
+#include <asm/ppc4xx-gpio.h>
 #include <asm/io.h>
 #include <nand.h>