timers: Expand clk forward logic beyond nohz

As for next_expiry, the base->clk catch up logic will be expanded beyond
NOHZ in order to avoid triggering useless softirqs.

If softirqs should only fire to expire pending timers, periodic base->clk
increments must be skippable for random amounts of time.  Therefore prepare
to catch-up with missing updates whenever an up-to-date base clock is
needed.

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/20200717140551.29076-10-frederic@kernel.org