bluetooth: controller: removing 'no-brainer' TODOs from refactored LLCP

Getting rid of TODOs that are fairly straight forward to resolve
* introduce role checks in ENC API
* Remove ASSERT on re-rx of LL_VERSION_IND, ignore instead
* in tests/.../ctrl_chmu: rename variable and initialize initial ch map
* in tests/.../mock_ctrl/util.c: Changing TODO into FYI
* in tests/.../helper_features.h update mask and remove TODO comment
* in ull_llcp_remote.c: re-order cases in proc_with_instant switch
* in ull_conn_upd.c: PARAM REQ only uses REJECT_EXT_IND
* in ull_llcp_common.c: in CENTRAL on rx of LL_MIN_USED_CHANNELS_IND
     chose to do nothing re. channel map. Update unit test accordingly

Signed-off-by: Erik Brockhoff <erbr@oticon.com>