anv: Fix sanitization of stencil state when the depth test is disabled

When depth testing is disabled, we shouldn't pay attention to the
specified depthCompareOp, and just treat it as always passing. Before,
if the depth test is disabled, but depthCompareOp is VK_COMPARE_OP_NEVER
(e.g. from the app having zero-initialized the structure), then
sanitize_stencil_face() would have incorrectly changed passOp to
VK_STENCIL_OP_KEEP.

v2: Roll the depthTestEnable check into the ds_aspect check below since
    they now both do the same thing.

Fixes: 028e1137 "anv/pipeline: Be smarter about depth/stencil state"
Signed-off-by: Alex Smith <asmith@feralinteractive.com>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
(cherry picked from commit 3bd239f7)