radeonsi/nir: Use NIR barycentric intrinsics

This is simpler than radv, since the driver_location is already assigned
for us.

Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>

src/amd/common/ac_nir_to_llvm.c

@@ -3341,6 +3341,12 @@ static void visit_intrinsic(struct ac_nir_context *ctx,
 	case nir_intrinsic_load_helper_invocation:
 		result = ac_build_load_helper_invocation(&ctx->ac);
 		break;
+	case nir_intrinsic_load_color0:
+		result = ctx->abi->color0;
+		break;
+	case nir_intrinsic_load_color1:
+		result = ctx->abi->color1;
+		break;
 	case nir_intrinsic_load_instance_id:
 		result = ctx->abi->instance_id;
 		break;

src/amd/common/ac_shader_abi.h

@@ -63,6 +63,8 @@ struct ac_shader_abi {
 	LLVMValueRef ancillary;
 	LLVMValueRef sample_coverage;
 	LLVMValueRef prim_mask;
+	LLVMValueRef color0;
+	LLVMValueRef color1;
 	/* CS */
 	LLVMValueRef local_invocation_ids;
 	LLVMValueRef num_work_groups;