x86 power: define RAPL MSRs

The Run Time Average Power Limiting interface
is currently model specific, present on Sandy Bridge
and Ivy Bridge processors.

These #defines correspond to documentation in the latest
"Intel® 64 and IA-32 Architectures Software Developer Manual",
plus some typos in that document corrected.

Signed-off-by: Len Brown <len.brown@intel.com>
Cc: x86@kernel.org