Remove access of DisplayClient from vr_wm

It seems like this functionality relied on another pending patch that
will not come into the picture just yet. I am not reverting the full set
of patches, as they contained some other changes which are best left in.

Bug: None
Test: *pending*
Change-Id: I2d6b6ec8ba6acc98388e5f13a54ad2cea25c1a00