Bluetooth: mgmt: rename update_*_data_for_instance()

The ...for_instance function name is quite long and does not follow the
..._inst_... convention followed elsewhere in the code. This patch
renames the ...for_instance functions to their shorter ..._inst_...
version.

Signed-off-by: Florian Grandel <fgrandel@gmail.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>