Support changing USB configuration without usb_configuration switch.

Some devices (read: Motorola devices) don't have an usb_configuration
switch provided by the kernel to announce USB reconfigurations, neither
does their kernel emit 'function changed' uevents. Instead, they use a
Java daemon interacting with a custom USB daemon via sockets to
reconfigure the USB. In order to support that scenario, do the
following:
- If a property ro.usb.use_custom_service is set, Listen for 'USB
  reconfigured' intents
- Switch off uevent listening in that case (so that uevent contents
  don't overwrite intent contents)
- When an uevent (or reconfiguration intent) arrive for a legacy device,
  do not only check the leagcy function path, but also the usb_composite
path