[d3d11] Initialize depth images to zero rather than one

Matches Windows behaviour.

src/d3d11/d3d11_initializer.cpp

@@ -181,7 +181,7 @@ namespace dxvk {
             image, value, subresources);
         } else {
           VkClearDepthStencilValue value;
-          value.depth   = 1.0f;
+          value.depth   = 0.0f;
           value.stencil = 0;
           
           m_context->clearDepthStencilImage(