timer: Lower base clock forwarding threshold

There is no apparent reason for not forwarding base->clk when it's 2
jiffies late, except perhaps for past optimizations. But since forwarding
has to be done at some point now anyway, this doesn't stand anymore.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: Juri Lelli <juri.lelli@redhat.com>