freedreno/a3xx/compiler: fix RECT textures

Whether or not the coords are normalized is handled in the texture
state.  But we otherwise need to treat RECT sample instructions as 2D.

Signed-off-by: Rob Clark <robclark@freedesktop.org>
WIP: xa: handle solid-fill src/mask
WIP: xa: remove unneeded args
WIP: xa: scissor to help tilers..
WIP: xa: reuse surfaces

Otherwise it will trick the gallium driver into thinking that the render
target has actually changed (due to different pipe_surface pointing to
same underlying pipe_resource).  This is really badness for tiling GPUs
like adreno.