Fix L2CAP ACL packet PB(Packet Boundary) flag for LE PDU.

ACL packet boundary flag should be 0 instead of 2 for LE PDU.
Some HCI will drop LE packet with PB flag is 2, and if sent,
some target may reject the packet.

PR: 248024
Reported by: Greg V
Reviewed by: Greg V, emax
Differential Revision: https://reviews.freebsd.org/D25704