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/drivers/block/sil680.c b/drivers/block/sil680.c
index 3ca64b9..b1db257 100644
--- a/drivers/block/sil680.c
+++ b/drivers/block/sil680.c
@@ -17,7 +17,7 @@
  * incorrect for the target board (e.g. the sequoia board requires 0).
  * #define CONFIG_SYS_PCI_CACHE_LINE_SIZE	0
  *
- * #define CONFIG_CMD_IDE
+ * #define CONFIG_IDE
  * #undef  CONFIG_IDE_8xx_DIRECT
  * #undef  CONFIG_IDE_LED
  * #undef  CONFIG_IDE_RESET