x86: Add trace point for MSR accesses

For debugging low level code interacting with the CPU
it is often useful to trace the MSR read/writes. This gives
a concise summary of PMU and other operations.

perf has an ad-hoc way to do this using trace_printk,
but it's somewhat limited (and also now spews ugly
messages when enabled)

Instead define real trace points for all MSR accesses.

This adds two new trace point: read_msr and write_msr.
They also report if the access faulted (if *_safe is used)

This allows filtering and triggering on specific
MSR values, which allows various more advanced
debugging techniques.

All the values are well defined in the CPU documentation.

I only added it to native MSR accesses in C, not paravirtualized
or in entry*.S (which is not too interesting)

Signed-off-by: Andi Kleen <ak@linux.intel.com>