audiopolicy: engineconfigurable: switch to unix socket for PFW debug

SEPolicy rule prevents the audioserver to use tcp / udp sockets.
The Parameter-framework has been updated to use unix socket.
This patch makes use of the unix socket and adds the corresponding
sepolicy rules.

Test: make
Change-Id: I61fcf6fec06a78cf3189c93a86469070ef15bba4
Signed-off-by: François Gaffie <francois.gaffie@renault.com>