Bluetooth: use inclusive language in HCI role comments

This patch replaces some non-inclusive terms based on the appropriate
language mapping table compiled by the Bluetooth SIG:
https://specificationrefs.bluetooth.com/language-mapping/Appropriate_Language_Mapping_Table.pdf



Specifically, these terms are replaced:
master -> initiator (for smp) or central (everything else)
slave  -> responder (for smp) or peripheral (everything else)

The #define preprocessor terms are unchanged for now to not disturb
dependent APIs.

Signed-off-by: Archie Pusaka <apusaka@chromium.org>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>