mtd: Hide CONFIG_MTD_BLKDEVS from the menu

Make this option a hidden one and get a cleaner configuration.
This option just selects a common infrastructure for MTD-based devices
to expose a block interface. There is no point in allowing a separate
enable/disable.
Signed-off-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
[Brian: keep symbol as tristate]
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

drivers/mtd/Kconfig

@@ -157,10 +157,11 @@ config MTD_BCM47XX_PARTS
 
 comment "User Modules And Translation Layers"
 
+#
+# MTD block device support is select'ed if needed
+#
 config MTD_BLKDEVS
-	tristate "Common interface to block layer for MTD 'translation layers'"
-	depends on BLOCK
-	default n
+	tristate
 
 config MTD_BLOCK
 	tristate "Caching block device access to MTD devices"