defconfig: 8953_64: enable default key driver

Enable default key driver to support metadata encryption.
File system metadata will be encrypted with a default
key generated during bootup.

Change-Id: I782d75969537c5f02981af1990368001c670be2a
Signed-off-by: Neeraj Soni <neersoni@codeaurora.org>
diff --git a/arch/arm64/configs/msm8953-perf_defconfig b/arch/arm64/configs/msm8953-perf_defconfig
index a66ea31..3039177 100644
--- a/arch/arm64/configs/msm8953-perf_defconfig
+++ b/arch/arm64/configs/msm8953-perf_defconfig
@@ -265,6 +265,7 @@
 CONFIG_BLK_DEV_DM=y
 CONFIG_DM_CRYPT=y
 CONFIG_DM_REQ_CRYPT=y
+CONFIG_DM_DEFAULT_KEY=y
 CONFIG_DM_UEVENT=y
 CONFIG_DM_VERITY=y
 CONFIG_DM_VERITY_FEC=y