qcacmn: Select valid channel after pcl selection fails

When SAP works in ACS mode, it needs to restart with a safe channel
if current channel is unsafe. Sometimes no channel is selected from
pcl channels. SAP can't just pick up one safe channel because the
channel may be DFS channel while SAP may disable DFS master capability.
SAP should select one valid channel for LTE COEX.

Change-Id: I303165f82b5c2a8d06447df4ba23fdcba5b1083c
CRs-Fixed: 2447147