This cleans up the x86-64 lost tick handling and fixes some issues:

First it moves that code into an own function.

The newer could would become very noisy when the machine loses timer ticks
regularly.  This happens often on some laptops etc.  during the acpi ec
access (nothing much can be really done about it) This patch prints the
warnings only once.

It also fixes the logic on when to ask cpufreq for a new estimate.

And it implements timer fallback to HPET when there are really lots of lost
ticks.  This is following i386.  PIT fallback isn't implemented right now
though, but I hope we don't need this.
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>