tools/power/turbostat: Abstract extended cstate MSRs support

Abstract the support for MSR_PKG_WEIGHTED_CORE_C0_RES,
MSR_PKG_ANY_CORE_C0_RES, MSR_PKG_ANY_GFXE_C0_RES and
MSR_PKG_BOTH_CORE_GFXE_C0_RES.

Delete has_skl_msrs() CPU model check.

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