qcacmn: For SAP use dwell_time_active def dwell time for 2g chan

Driver uses dwell_time_active_2g by default for scan. In case if
ACS enabled on driver, The dwell_time_active_2g (80 msec) result
in ACS latency and thus latency in SAP start.

To optimize SAP turn-on time latency, use dwell_time_active_def
as dwell time for 2g channels instead of well_time_active_2g
during ACS scan.

Change-Id: Ib673284c99e5539abe0268319e04cc63d0cbb98f
CRs-Fixed: 2383308