Audio V4: Copy 2.0 .hal files in 4.0

That will ease review of the changes.
The only changes are:
 - replace all @2.0 by 4.0
   $ sed -i 's/@2\.0/@4\.0/g' */4.0/*.hal
 - replace all licence 2016 by 2018
   $ sed -i 's/2016/2018/g' */4.0/*.hal

Moving the .hal in a subfolder forces the package name and the
namespace to change.

This mean that the audio HAL 2.0 and 4.0 will not be consider
different version of the same HAL but two different HALs.

As a result to minimize code change due to tight deadline,
keep the 4.0 core in the audio folder.

Bug: 38184704
Test: hardware/interfaces/update-makefiles.sh
Change-Id: I7c7a826270c9933091f037b795806787e1284583
Signed-off-by: Kevin Rocard <krocard@google.com>