wlan: Reject ext scan commands on non sta ifaces

Ext scan should be used only for STA interface,
In some cases user space is sending extended scan for
non-station interfaces also.
Reject all extended scan related commands for non-station
interface.

Change-Id: I6313d1eb7374d681f133d7dd6a855f85b8eba99b
CRs-Fixed: 2349917