P2P: Allow P2P functionality to be disabled per interface

P2P: Allow P2P functionality to be disabled per interface

By default, P2P is initialized for all driver interfaces and this makes
P2P getting initialized for non-P2P station interface if the supplicant
is started first on this interface. If an interface is dedicated for
non-P2P station mode, it is now possible to disable P2P initialization
by adding 'p2p_disabled=1' in the configuration file of non-P2P station
interface, irrespective of the order in which supplicant is started.

Signed-hostap: Sreenath Sharma <sreenats@broadcom.com>