RSSI in the scan entry is a negative value. It was converted to positive
value and if the converted value is greater than WLAN_RSSI_DUMMY_MARKER
(has positive value 295), util_scan_entry_rssi() was returning 0 to the
caller.
util_scan_entry_rssi() is used for printing RSSI value. Since RSSI is saved
as a negative value and caller expects it as a negative value, return a
negative RSSI value from util_scan_entry_rssi().
Change-Id: Ifdeb88dfa42a6927ff29670429d846ff071e9c59
CRs-Fixed: 2576129
cccf40f12b