x86, perf: Trace rdpmc too

perf uses RDPMC to read the performance counters, so it's useful to trace
that too. Add a trace point for RDPMC too, similar to the existing
MSR ones. Since there is only a single call of rdpmc in the whole kernel
(in perf)
just add the trace statement to that call, instead of moving the rdpmcl
inline out of line.

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