perf/probes: Improve command-line option of perf-probe

perf/probes: Improve command-line option of perf-probe

Change command-line option from -P to --add, and accepting
probes without --add too.

  perf probe --add "probe-define"

or, just:

  perf probe "probe-define"

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Frank Ch. Eigler <fche@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jason Baron <jbaron@redhat.com>
Cc: K.Prasad <prasad@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
LKML-Reference: <20091027204301.30545.48600.stgit@harusame>
Signed-off-by: Ingo Molnar <mingo@elte.hu>