Had to change some listener ports from 1521 to 8001 on a RAC environment recently here are the steps taken.

1. Check the listener status

[oracle@test0101 20299013]$ srvctl status listener -l LISTENER
Listener LISTENER is enabled
Listener LISTENER is running on node(s): test0101,test0102


2. Modify the listener

[oracle@test0101 20299013]$ srvctl modify listener -l LISTENER -p 8001


3. Bounce the listener
[oracle@test0101 20299013]$ srvctl stop listener
[oracle@test0101 20299013]$ srvctl start listener

4. Change the MGMTDB listener
[oracle@test0101 20299013]$ srvctl status listener -l MGMTLSNR
Listener MGMTLSNR is enabled
Listener MGMTLSNR is running on node(s): test0101
[oracle@test0101 20299013]$ srvctl modify listener -l MGMTLSNR -p 8001


5. Restart the MGMTDB listener
Had to also restart the MGMTDB database before restarting the listener
[oracle@test0101 20299013]$ srvctl stop MGMTLSNR
PRCR-1065 : Failed to stop resource ora.MGMTLSNR
CRS-2529: Unable to act on 'ora.MGMTLSNR' because that would require stopping or relocating 'ora.mgmtdb', but the force option was not specified
[oracle@test0101 20299013]$ srvctl stop MGMTDB
[oracle@test0101 20299013]$ srvctl stop MGMTLSNR
[oracle@test0101 20299013]$ srvctl start MGMTLSNR
[oracle@test0101 20299013]$ srvctl start MGMTDB

6. Scan Listener already at 8001
[oracle@test0101 20299013]$ srvctl config scan_listener
SCAN Listener LISTENER_SCAN1 exists. Port: TCP:8001
Registration invited nodes:
Registration invited subnets:
SCAN Listener is enabled.
SCAN Listener is individually enabled on nodes:
SCAN Listener is individually disabled on nodes:
SCAN Listener LISTENER_SCAN2 exists. Port: TCP:8001
Registration invited nodes:
Registration invited subnets:
SCAN Listener is enabled.
SCAN Listener is individually enabled on nodes:
SCAN Listener is individually disabled on nodes:
SCAN Listener LISTENER_SCAN3 exists. Port: TCP:8001
Registration invited nodes:
Registration invited subnets:
SCAN Listener is enabled.
SCAN Listener is individually enabled on nodes:
SCAN Listener is individually disabled on nodes: