freedreno/ir3: add image/ssbo <-> ibo/tex mapping

freedreno/ir3: add image/ssbo <-> ibo/tex mapping

Images and SSBOs don't map directly to the hw.  They end up being part
texture and part something else.  Starting with a6xx, the hack used for
a5xx to smash the image tex state into hw texture state starting from
MAX counting down won't work, because we start using tex state also for
SSBO read.

Signed-off-by: Rob Clark <robdclark@gmail.com>