[SPIN]Set interface callback during scan request

[Cause] Inteface callback was not being called in error case when 'scan done'
        signal was received from wpasupplicant and hence the 'scanning' state
        was not being set properly
[Solution] Set the interface callback during scan request which gets called back
           and sets the 'scanning' state properly during error cases

Change-Id: I1ac96a7657bee12ee642f8b680a5b7ef51118048
Signed-off-by: Niraj Kumar Goit <niraj.g@samsung.com>