wifi(implementation): Send NAN disabled on wlan0 down & up

When the iface state is toggled for MAC address change on the underlying
interface for NAN operations, send NAN disabled event up to the
framework. The iface down/up toggle resets all NAN operations in the
firmware. So, this callback should trigger a cleanup of any
operations initiated by the framework.

Bug: 132943959
Test: Unit tests in the follow-up CL.
Test: Will send for regression tests.
Change-Id: I760dc5ca3b9276956f5edd40a97c3c13811f442c