perf record: Amend option summaries

perf record: Amend option summaries

Because there's too many options and I cannot read, I frequently get
confused between -c and -P, and try to do things like:

  perf record -P 50000 -- foo

Which does not work; try and make the option description slightly longer
and hopefully less confusing.

Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
[ Do those changes on the man page as well ]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>