tools/power/turbostat: Abstract Nehalem MSRs support

MSR_PLATFORM_INFO, MSR_IA32_TEMPERATURE_TARGET, MSR_SMI_COUNT,
MSR_PKG_CST_CONFIG_CONTROL, and the TRL MSRs are always available for
platforms since Nehalem. Support for these msrs can be described
altogether.

Abstract the support for these MSRs.

Delete probe_nhm_msrs() CPU model check.
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Reviewed-by: Len Brown <len.brown@intel.com>