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/arch/powerpc/cpu/mpc5xxx/ide.c b/arch/powerpc/cpu/mpc5xxx/ide.c
index 9003b77..d1f4349 100644
--- a/arch/powerpc/cpu/mpc5xxx/ide.c
+++ b/arch/powerpc/cpu/mpc5xxx/ide.c
@@ -8,7 +8,7 @@
  */
 #include <common.h>
 
-#if defined(CONFIG_CMD_IDE)
+#if defined(CONFIG_IDE)
 #include <mpc5xxx.h>
 
 DECLARE_GLOBAL_DATA_PTR;