Kconfig: Add a CONFIG_IDE option

At present IDE support is controlled by CONFIG_CMD_IDE. Add a separate
CONFIG_IDE option so that IDE support can be enabled without requiring
the 'ide' command.

Update existing users and move the ide driver into drivers/block since
it should not be in common/.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/board/freescale/m54455evb/m54455evb.c b/board/freescale/m54455evb/m54455evb.c
index d6b0650..1e35970 100644
--- a/board/freescale/m54455evb/m54455evb.c
+++ b/board/freescale/m54455evb/m54455evb.c
@@ -88,7 +88,7 @@
 	return (0);
 }
 
-#if defined(CONFIG_CMD_IDE)
+#if defined(CONFIG_IDE)
 #include <ata.h>
 
 int ide_preinit(void)