bluez5_utils: rename options to have the proper suffix

The bluez5_utils Config.in options had a bogus prefix:
BR2_PACKAGE_BLUEZ5 instead of the expected
BR2_PACKAGE_BLUEZ5_UTILS. This commit fixes that, and adds the
appropriate Config.in.legacy handling.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Acked-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>