Revert "wlan: Provide runtime option to enable or disable rssi threshold (settings)"

This reverts commit d6b8cbb1.

RSSI threshold parameters are now user configurable.Below are the
parameters.
THRESHOLD_UNBLACKLIST_HARD_5G
THRESHOLD_UNBLACKLIST_SOFT_5G
THRESHOLD_UNBLACKLIST_HARD_24G
THRESHOLD_UNBLACKLIST_SOFT_24G
THRESHOLD_INITIAL_AUTO_JOIN_ATTEMPT_RSSI_MIN_5G
THRESHOLD_INITIAL_AUTO_JOIN_ATTEMPT_RSSI_MIN_24G
Hence reverting the gerrit

Change-Id: If40cc281f8d13a9c3255e4306db45bc3ef4002ac
CRs-Fixed: 757958