Use 0000 as pin key for PORCHE_PAIRING_CONFLICT issue

For PORCHE_PAIRING_CONFLICT issue when there are no other paired devices
available in bluetooth list pairing always fails (as per implementation
in bluedroid stack).
In this case when pin key request is received use 0000 as the pin key
so that pairing is successful.

Bug 67614

Change-Id: I67b2e689cfcc52c93fdda62dd742812698baa0e6
Bluetooth: Adding Sniff feature for PAN Profile

Sniff feature for PAN profile was not implemented in power
manager module of the stack, which was causing higher power
consumption after connecting PAN profile, Even though PAN
ACL link is idle & there is no data communication between
DUT & remote device. Adding sniff feature for PANU role &
NAP role to reduce power consumption.

Change-Id: Idf568f53a317abd536edf34fbdf1733fdf53b7d0
Merge "Bluetooth: Adding Sniff feature for PAN Profile"
Merge "Use 0000 as pin key for PORCHE_PAIRING_CONFLICT issue"
fix up build issues