m: enable dm-verity rootfs

This makes all the existing EFI unified kernel images boot from a
dm-verity rootfs.

Change-Id: Iac05942e40b81825252e84feb5c79c8ff215680a
Reviewed-on: https://review.monogon.dev/c/monogon/+/527
Reviewed-by: Sergiusz Bazanski <serge@monogon.tech>
diff --git a/third_party/linux/linux-metropolis.config b/third_party/linux/linux-metropolis.config
index b18213e..b584a0c 100644
--- a/third_party/linux/linux-metropolis.config
+++ b/third_party/linux/linux-metropolis.config
@@ -1582,7 +1582,7 @@
 # CONFIG_DM_MULTIPATH is not set
 # CONFIG_DM_DELAY is not set
 # CONFIG_DM_DUST is not set
-# CONFIG_DM_INIT is not set
+CONFIG_DM_INIT=y
 # CONFIG_DM_UEVENT is not set
 # CONFIG_DM_FLAKEY is not set
 CONFIG_DM_VERITY=y