binding/python: use SWIG_FromCharPtrAndSize for Python3 support

PyString_FromStringAndSize is replaced with PyUnicode_FromStringAndSize
in Python3, and SWIG_FromCharPtrAndSize will choose the right one with
the check "#if PY_VERSION_HEX >= 0x0300000".

Fixes: 4cb7829debd7 ("add support for hw address manipulation")
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
1 file changed