turbostat prints the abnormal SYS%LPI across suspend-to-idle:
SYS%LPI = 114479815993277.50

This is reproduced by:
Run a freeze cycle, e.g. "sleepgraph -m freeze -rtcwake 15".
Then do a reboot. After boot up, launch the suspend-idle-idle
and check the SYS%LPI field.

The slp_so residence counter is in LPIT table, and BIOS does not
clears this register across reset. The PMC expects the OS to calculate
the LPI residency based on the delta. However, there is an firmware
issue that the LPIT gets cleared to 0 during the second suspend
to idle after the reboot, which brings negative delta value.

[lenb: updated to print "neg" upon this BIOS failure]
Reported-by: Todd Brandt <todd.e.brandt@intel.com>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>