Audio V4: Fix doc comments for hidl-doc

hidl-doc does not support two consecutive documentation comments
/** ... */
/** ... */

In such case make the first one a non-doc comment.

This is a port of: http://android-review.googlesource.com/432140



Bug: 38184704
Test: none
Change-Id: I86cb10c655036ca49055ee007813c3e5af743eb5
Signed-off-by: Kevin Rocard <krocard@google.com>