ftrace: Separate unlimited probes from count limited probes

The function tracing probes that trigger traceon or traceoff can be
set to unlimited, or given a count of # of times to execute.

By separating these two types of probes, we can then use the dynamic
ftrace function filtering directly, and remove the brute force
"check if this function called is my probe" routines in ftrace.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>