The dEQP unpack buffer tests were failing because they use a max and
base level of zero with mipmapping enabled. Update our sampler
completeness checks to account for min and max level.

We'll have to dig in to our code to find corner cases in D3D with
base and max level.

Change-Id: I74357c6dc2e1908d0463d2e5cbc8ee91b61a3b7f
Reviewed-on: https://chromium-review.googlesource.com/240763Reviewed-by: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Brandon Jones <bajones@chromium.org>
Tested-by: Jamie Madill <jmadill@chromium.org>