tools/power turbostat: IVB Xeon: fix --debug regression

Staring in Linux-4.3-rc1,
commit 6fb3143b ("tools/power turbostat: dump CONFIG_TDP")
touches MSR 0x648, which is not supported on IVB-Xeon.
This results in "turbostat --debug" exiting on those systems:

turbostat: /dev/cpu/2/msr offset 0x648 read failed: Input/output error

Remove IVB-Xeon from the list of machines supporting with that MSR.

Signed-off-by: Len Brown <len.brown@intel.com>