timers: Lower base clock forwarding threshold

There is nothing that prevents from forwarding the base clock if it's one
jiffy off. The reason for this arbitrary limit of two jiffies is historical
and does not longer exist.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Juri Lelli <juri.lelli@redhat.com>
Link: https://lkml.kernel.org/r/20200717140551.29076-13-frederic@kernel.org