Separating uprobe sensor setup into addUprobe function, that creates
and sets up uprobeEntry object and createSingleUprobeSensor that
creates the actual sensor progs/maps arrays.

This way we can easily add multi uprobe sensor create function in
following changes.

Signed-off-by: Jiri Olsa <[email protected]>

Just to keep it consistent. At the moment we don't use the return
value to trigger the return probe, but it's the plan for the future.

Signed-off-by: Jiri Olsa <[email protected]>