qcacmn: Add support for lower span active and passive dwell time

Add LOW_SPAN_ACTIVE_DWELL_TIME and LOW_SPAN_PASSIVE_DWELL_TIME
macro support to keep all 2.4g/5g active/passive dwell time
same for low span scan mode.

Disable adaptive dwell to firmware so that firmware cannot
modify dwell time.

Change-Id: Iff05dd7b37a40226c61b28a1e59ea8aa8c57cb52
CRs-Fixed: 3076163