buildroot

python: align the target finalize hooks with python3

Since the bump of python3 to 3.5.x, the target finalize hooks
registered by the python3 have been changed a little bit. For the sake
of consistency, this commit aligns the target finalize hooks
registered by the python package so that they look the same as the
ones used by python3.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Reviewed-by: Samuel Martin <s.martin49@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>