mtd: of_parts: fix breakage in Kconfig

MTD_OF_PARTS and the default setting is not working due to using 'Y'
instead of 'y', introduced in commit
d6137badeff1ef64b4e0092ec249ebdeaeb3ff37. This made our board, and
possibly other boards using DTS defined partitions and not having
CONFIG_MTD_OF_PARTS=y defined in the defconfig, fail to mount root.

Signed-off-by: Frank Svendsboe <frank.svendsboe@gmail.com>
Cc: stable@kernel.org [3.2+]
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
diff --git a/drivers/mtd/Kconfig b/drivers/mtd/Kconfig
index 5760c1a..27143e0 100644
--- a/drivers/mtd/Kconfig
+++ b/drivers/mtd/Kconfig
@@ -128,7 +128,7 @@
 
 config MTD_OF_PARTS
 	tristate "OpenFirmware partitioning information support"
-	default Y
+	default y
 	depends on OF
 	help
 	  This provides a partition parsing function which derives