[media] vivi: Kill TSTAMP_* macros

Usage of TSTAMP_* macros has gone in 2010 in 730947bc (V4L/DVB: vivi:
clean up and a major overhaul) but the macros remain. Say goodbye to
them.

Signed-off-by: Kirill Smelkov <kirr@mns.spb.ru>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>