qcacld-3.0: Don't add duplicate frequencies in pcl list

Currently if SCC frequencies are added in pcl list and
rest 5 GHz frequencies are required to be added with lesser
weightage then all 5 GHz/6 GHz frequencies are added including
SCC channels. so in pcl duplicate entries are found for SCC
frequencies with different weightage.

Fix is not to add SCC frequencies during addition of 5 GHz/6 GHz
frequencies if SCC frequencies are already present in pcl.

Change-Id: I03123e4bf8caee62b0fcd0c3ae78d6cd7187c7de
CRs-Fixed: 3209858