powercap: intel_rapl: Support per domain energy/power/time unit

RAPL MSR/MMIO Interface has package scope unit register but some RAPL
domains like Dram/Psys may use a fixed energy unit value instead of the
default unit value on certain platforms.
RAPL TPMI Interface supports per domain unit register.

For the above reasons, add support for per domain unit register and per
domain energy/power/time unit.

When per domain unit register is not available, use the package scope
unit register as the per domain unit register for each RAPL domain so
that this change is transparent to MSR/MMIO Interface.

No functional change intended.

Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Tested-by: Wang Wendy <wendy.wang@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>