Audio HAL VTS: Avoid copying Return in helper

Return are movable only, thus the fact that assertResult took a copy of
the value meant that the callee had to provide an rvalue.

This was not needed as the Result was not modified. Change it to a const
reference.

Test: run test on board

Bug: 34170075
Signed-off-by: Kevin Rocard <krocard@google.com>
1 file changed