Fix regression introduced in r8525 which increased ECM times a lot.

r8525 (Reliably stop check() thread on exit) changed nanosleep to
pthread_timed_condwait() but rounded the sleep time to the nearest
second missing the fact that this check_thread drives ECM answers.
The effect was massive increase in ECM response times.

Thanks to wimpie007 for the report.

git-svn-id: http://streamboard.de.vu/svn/oscam/trunk@8551 4b0bc96b-bc66-0410-9d44-ebda105a78c1