policy_hal: update custom audio policy APIs against AOSP

1) Update startSource() and stopSource() input parameter
outputDesc to align with AOSP.

2) audio policy: broadcast device connect event before refreshing profiles
This patch broadcasts the connect device event before checking and reloading
capabilities of profiles.
It allows the HAL implementor to use connect / disconnect event to respectively
load / reset capabilities of devices that has dynamic capabilities (e.g. HDMI).
Change-Id: Ie0533da25fed89cb9e5bbfc5b1fc886b3176837d

CRs-fixed: 2056377
Change-Id: I15c877be8cdb85d1cb4b52a8b379ac254df3dca2