irqtest: Fix pass condition to what description says
irqtest: Fix pass condition to what description says

Allow 5 instead of 4 missed interrupts.

Signed-off-by: Moritz Hoffmann <53ba0aa052d551db5cb133c62d34e71044d0deba@inf.ethz.ch>

kishoredbn/barrelfish,BarrelfishOS/barrelfish,BarrelfishOS/barrelfish,kishoredbn/barrelfish,BarrelfishOS/barrelfish,kishoredbn/barrelfish,kishoredbn/barrelfish,BarrelfishOS/barrelfish,BarrelfishOS/barrelfish,kishoredbn/barrelfish,kishoredbn/barrelfish,BarrelfishOS/barrelfish,BarrelfishOS/barrelfish,BarrelfishOS/barrelfish,BarrelfishOS/barrelfish