defconfig: Enable dm-verity for 8916 target

This change will enable CONFIG_DM_VERITY
config for 8916, which is used for
dm-verity feature.

Change-Id: I1751c0f6f35ec4c07918e4596961e2ae88b14dc1
Signed-off-by: Mishra Mahima <mahima@codeaurora.org>