defconfig: Enable dm-verity for 8084, 8916 and 8994 targets

Enable CONFIG_DM_VERITY for 8084, 8916 and 8994 targets.  With
corresponding userspace support, this allows block-level
integrity checking of block storage devices (e.g. ensuring
storage contents did not change).

Change-Id: Ie1fd72ae6d514a165a480953155b569f32c3f99a
Signed-off-by: Ajay Dudani <adudani@codeaurora.org>
Signed-off-by: David Ng <dave@codeaurora.org>