OBEX: Reduce Obex MTU size for A2DP or SCO concurrency

Reduce Obex MTU to 8k from 64k when OPP send is tried with
SCO / A2DP streaming in progress, so that the continue
response for first complete Obex PUT packet is received
from SOC within 50 seconds time frame.

CRs-Fixed: 571865
Change-Id: I1eae114f57f2a92ee4b26c82d8f55fafe02775b8
Bluetooth: Changes for LPP and extended LE scan

This patch includes implementation of a new Bluetooth
Adapter named QBluetoothAdapter for implementing LE
specific tasks that the default adapter doesnt perform.
This patch also implements Low power proximity and extended
LE scan functionality based on service UUIDs.

CRs-Fixed: 581289
Change-Id: I63e0593f79c8929d4e18cee0472fcb401c8892e7