powercap/intel_rapl: Support multi-die/package

RAPL "package" domains are actually implemented in hardware per-die.
Thus, the new multi-die/package systems have mulitple domains
within each physical package.

Update the intel_rapl driver to be "die aware" -- exporting multiple
domains within a single package, when present.  No change on single
die/package systems.

Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: linux-pm@vger.kernel.org
Link: https://lkml.kernel.org/r/9fcb4719aeb7efccf3bc75ed8dd559e46121649f.1557769318.git.len.brown@intel.com