Revert "clocksource: Load the ACPI PM clocksource asynchronously"

Revert "clocksource: Load the ACPI PM clocksource asynchronously"

This reverts commit be1d2c7f597ef524c0b73cbfea8f936bbd83d62c.

The reason for this revert is that making the frequency verification
preemptible and interruptible is not working reliably. Michaels
machine failed to use PM-timer with the message:

  PM-Timer running at invalid rate: 113% of normal - aborting.

That's not a surprise as the frequency verification does rely on
interrupts being disabled. With a async scheduled thread there is no
guarantee to achieve the same result. Also some driver might fiddle
with the CTC channel 2 during the verification period, which makes the
result even more random and unpredictable.

This can be solved by using the same mechanism as we use in the
deferred TSC validation code, but that only will work if we verified a
working HPET _BEFORE_ trying to do the PM-Timer lazy validation.

So for now reverting is the safe option.

Bisected-by: Michael Witten <mfwitten@gmail.com>
Cc: Arjan van de Ven <arjanvandeven@gmail.com>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: John Stultz <johnstul@us.ibm.com>
Cc: Len Brown <lenb@kernel.org>
LKML-Reference: <alpine.LFD.2.02.1204112303270.2542@ionos>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>