This fixes cases where the 3D path is used with layered rendering.

Fixes dEQP-VK.renderpass.suballocation.multisample_resolve.layers* failures

Note the blob's 3D fallback path behaves differently, and uses the
framebuffer information to clear each layer individually (changing the MRT
state each time). But that's not possible in all cases, and the blob fails
to clear properly in dEQP-VK.geometry.layered.*.secondary_cmd_buffer cases.
So this clear path is not based on the blob's behavior.

Signed-off-by: Jonathan Marek <jonathan@marek.ca>
Part-of: <mesa/mesa!5426>