With the structured logging it makes more sense to tune this down a
bit. Also, this way it is consistent with Thomas Wood's new activity
indicator helper.
Spotted while discussing Thomas' patch with him.
v2: Thomas noticed that I've forgotten the fflush. Extract
igt_interactive_info for both igt_progress and igt_print_activity.
v3: Interactive output should go to stderr. Also extract the "is this
a terminal" check.
Cc: Thomas Wood <thomas.wood@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>