Revert "asahi: Advertise dual-source blending"

This reverts commit f4e2b22646.

This is broken until GL3 is enabled, possibly due to a core Mesa bug,
but it's a corner case not worth fixing.

Fixes Chromium.

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/22353>

docs/features.txt

@@ -99,7 +99,7 @@ GL 3.2, GLSL 1.50 --- all DONE: freedreno, i965, nv50, nvc0, r600, radeonsi, llv
 
 GL 3.3, GLSL 3.30 --- all DONE: freedreno, i965, nv50, nvc0, r600, radeonsi, llvmpipe, softpipe, virgl, zink, d3d12
 
-  GL_ARB_blend_func_extended                            DONE (freedreno/a3xx, freedreno/a6xx, panfrost, lima, asahi)
+  GL_ARB_blend_func_extended                            DONE (freedreno/a3xx, freedreno/a6xx, panfrost, lima)
   GL_ARB_explicit_attrib_location                       DONE (all drivers that support GLSL)
   GL_ARB_occlusion_query2                               DONE (v3d, panfrost, asahi)
   GL_ARB_sampler_objects                                DONE (all drivers)

src/asahi/lib/agx_nir_lower_tilebuffer.c

@@ -29,7 +29,7 @@ tib_filter(const nir_instr *instr, UNUSED const void *_)
       return false;
 
    nir_io_semantics sem = nir_intrinsic_io_semantics(intr);
-   assert(sem.dual_source_blend_index == 0 && "dual source blending lowered");
+   assert(sem.dual_source_blend_index == 0 && "todo: dual source blending");
    return (sem.location >= FRAG_RESULT_DATA0);
 }
 

src/gallium/drivers/asahi/agx_pipe.c

@@ -1355,8 +1355,9 @@ agx_get_param(struct pipe_screen *pscreen, enum pipe_cap param)
    case PIPE_CAP_FBFETCH:
    case PIPE_CAP_FBFETCH_COHERENT:
       return 8;
+
    case PIPE_CAP_MAX_DUAL_SOURCE_RENDER_TARGETS:
-      return 1;
+      return 0;
 
    case PIPE_CAP_OCCLUSION_QUERY:
    case PIPE_CAP_GENERATE_MIPMAP: