oprofile, x86: Check IBS capability bits 1 and 2

There are IBS CPUID feature flags in CPUID Fn8000_001B to detect if
the cpu supports IBS fetch sampling (FetchSam) and/or IBS execution
sampling (OpSam). This patch adds checks if the both features are
available.

Spec:

 http://support.amd.com/us/Processor_TechDocs/31116.pdf



Signed-off-by: Robert Richter <robert.richter@amd.com>