ANDROID: android-x86_64_defconfig: Enable CONFIG_DM_BOW

This is required to mount userdata (see b/398318965 for more
background). It's already enabled in the GKI config, but reven has not
yet switched to that.

Bug: 419874807
Test: Reven build successfully boots on T14
Change-Id: I5117407e89438c1b0ab67f780d196260bc2f7de7
Signed-off-by: Nicholas Bishop <nicholasbishop@google.com>