py80211: set policy for WIPHY_BANDS attribute

nl80211_policy does not specify all attributes, which makes them
default to NLA_UNSPEC. Add NLA_NESTED type for the WIPHY_BANDS
attribute.

Signed-off-by: Arend van Spriel <aspriel@gmail.com>
py80211: separate object string representation

The py80211 objects are used in a scripted environment and
there may not be an immediate need to have a string representation
of it. By seperating this from the object the user can choose if
he wants it or not.

Signed-off-by: Arend van Spriel <aspriel@gmail.com>
py80211: add example folder with wiphy retrieval example

Having an example may help understand the python library so
here is a first one, which list wiphy band related information.

Signed-off-by: Arend van Spriel <aspriel@gmail.com>
py80211: remove test code from library file

With examples folder introduced remove test code from the
python library file.

Signed-off-by: Arend van Spriel <aspriel@gmail.com>
Merge branch 'master' into wl-next

 examples/example01.py   |   10 +++++
 lib/cli.py              |  115 +++++++++++++++++++++++++++++++++++++++++++++++
 lib/generated/policy.py |    1 +
 lib/wiphy.py            |   60 -------------------------
 4 files changed, 126 insertions(+), 60 deletions(-)
 create mode 100644 examples/example01.py
 create mode 100644 lib/cli.py

Signed-off-by: Arend van Spriel <aspriel@gmail.com>