Bluetooth: Provide more config options to init sample

This allows to excersize different kconfig configurations in
single app. Thanks to this other samples don't have to get
extra extra options enabled just to improve test build coverage.

Change-Id: Ie5d261f3d38c60e227cf963d938b6fac6d0fb3b9
Signed-off-by: Szymon Janc <ext.szymon.janc@tieto.com>