bluedroid: Fix build with gcc 4.8

In gcc 4.8, the warning for unused parameters is enabled by
default - causing -Werror to break the build.

Change-Id: Ifa4dbc6a7cfec0c82486906ecf3ed6d53a550c3f
Signed-off-by: Bernhard Rosenkränzer <Bernhard.Rosenkranzer@linaro.org>