gallium: add PIPE_CAP_TGSI_BALLOT

Reviewed-by: Marek Olšák <marek.olsak@amd.com>

src/gallium/drivers/softpipe/sp_screen.c

@@ -300,6 +300,7 @@ softpipe_get_param(struct pipe_screen *screen, enum pipe_cap param)
    case PIPE_CAP_TGSI_CLOCK:
    case PIPE_CAP_POLYGON_MODE_FILL_RECTANGLE:
    case PIPE_CAP_SPARSE_BUFFER_PAGE_SIZE:
+   case PIPE_CAP_TGSI_BALLOT:
       return 0;
    case PIPE_CAP_SHADER_BUFFER_OFFSET_ALIGNMENT:
       return 4;