commit 3f93d1ad upstream.

V4L: pvrusb2: Keep MPEG PTSs from drifting away

This change was empirically figured out by Boris Dores after
empirically comparing against behavior in the Windows driver.
Signed-off-by: Mike Isely <isely@pobox.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>