v3d: do not report alpha-test as supported

This triggers lowering in the state-tracker, which makes things a bit
simpler.

Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7251>

src/broadcom/compiler/nir_to_vir.c

@@ -2439,11 +2439,6 @@ ntq_emit_intrinsic(struct v3d_compile *c, nir_intrinsic_instr *instr)
                                vir_uniform(c, QUNIFORM_VIEWPORT_Z_OFFSET, 0));
                 break;
 
-        case nir_intrinsic_load_alpha_ref_float:
-                ntq_store_dest(c, &instr->dest, 0,
-                               vir_uniform(c, QUNIFORM_ALPHA_REF, 0));
-                break;
-
         case nir_intrinsic_load_line_coord:
                 ntq_store_dest(c, &instr->dest, 0, vir_MOV(c, c->line_x));
                 break;

src/broadcom/compiler/vir.c

@@ -972,12 +972,6 @@ v3d_nir_lower_fs_late(struct v3d_compile *c)
         if (c->fs_key->clamp_color)
                 NIR_PASS_V(c->s, nir_lower_clamp_color_outputs);
 
-        if (c->fs_key->alpha_test) {
-                NIR_PASS_V(c->s, nir_lower_alpha_test,
-                           c->fs_key->alpha_test_func,
-                           false, NULL);
-        }
-
         /* In OpenGL the fragment shader can't read gl_ClipDistance[], but
          * Vulkan allows it, in which case the SPIR-V compiler will declare
          * VARING_SLOT_CLIP_DIST0 as compact array variable. Pass true as

src/gallium/drivers/v3d/v3d_screen.c

@@ -259,6 +259,9 @@ v3d_screen_get_param(struct pipe_screen *pscreen, enum pipe_cap param)
         case PIPE_CAP_UMA:
                 return 1;
 
+        case PIPE_CAP_ALPHA_TEST:
+                return 0;
+
         /* Geometry shaders */
         case PIPE_CAP_MAX_GEOMETRY_TOTAL_OUTPUT_COMPONENTS:
                 /* Minimum required by GLES 3.2 */