Remove IAPP functionality from hostapd

Remove IAPP functionality from hostapd

IEEE Std 802.11F-2003 was withdrawn in 2006 and as such it has not been
maintained nor is there any expectation of the withdrawn trial-use
recommended practice to be maintained in the future. Furthermore,
implementation of IAPP in hostapd was not complete, i.e., only parts of
the recommended practice were included. The main item of some real use
long time ago was the Layer 2 Update frame to update bridges when a STA
roams within an ESS, but that functionality has, in practice, been moved
to kernel drivers to provide better integration with the networking
stack.

Signed-off-by: Jouni Malinen <j@w1.fi>