freedreno/ir3: allow layer/viewport output for VS/GS/DS

With VK_EXT_shader_viewport_index_layer, these stages can all output the
viewport or layer id, and not just GS anymore.

Signed-off-by: Jonathan Marek <jonathan@marek.ca>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5832>
1 file changed