tools/power/turbostat: Abstract IRTL support

Abstract the support for MSR_PKGC3/PKGC6/PKGC7/PKGC8/PKGC9/PKGC10_IRTL.

Delete has_snb_msrs() CPU model check.

Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Reviewed-by: Len Brown <len.brown@intel.com>