radeonsi: fix unigine heaven crash when use aco on gfx8/9
Unigine Heaven crash on GFX8/9 when use aco: heaven_x64: ../../amd/mesa/src/gallium/drivers/radeonsi/si_nir_lower_abi.c:813: lower_tex: Assertion `samp_index >= 0 && comp_index >= 0' failed.
GFX8/9 will clamp texture comparison value in si_nir_lower_abi, but it has to be done after si_nir_lower_resource.
Fixes: ae933169 ("radeonsi: lower NIR resource srcs to descriptors last")