Kernel 5.4 lockdown smbios-thermal

Hello,
After upgraded Kubuntu from 18.04 to 20.04 on my Dell XPS 9370, I had a lot of message in dmesg (syslog), 3 for seconds:
```
May 11 16:04:37 PC kernel: [11151.455983] Lockdown: smbios-thermal-: /dev/mem,kmem,port is restricted; see man kernel_lockdown.7
May 11 16:04:37 PC kernel: [11151.518526] Lockdown: smbios-thermal-: /dev/mem,kmem,port is restricted; see man kernel_lockdown.7
May 11 16:04:37 PC kernel: [11151.582267] Lockdown: smbios-thermal-: /dev/mem,kmem,port is restricted; see man kernel_lockdown.7
May 11 16:04:39 PC kernel: [11153.460670] Lockdown: smbios-thermal-: /dev/mem,kmem,port is restricted; see man kernel_lockdown.7
May 11 16:04:39 PC kernel: [11153.520345] Lockdown: smbios-thermal-: /dev/mem,kmem,port is restricted; see man kernel_lockdown.7
May 11 16:04:39 PC kernel: [11153.596393] Lockdown: smbios-thermal-: /dev/mem,kmem,port is restricted; see man kernel_lockdown.7
```
I know the issue is due to Secure Boot, but I would not disable it. Everything works fine, so I would like to know if is possible to limit the access of smbios-thermal to /dev/mem,kmem,port, whereas their lack of access is not causing problems.
Thanks in advance,
Salvatore

# System Info:

```
- Distributor ID: Kubuntu
- Description: Kubuntu Focal Fossa
- Release: 20.04
- Kernel: Linux u-27469 5.4.0-26-generic
```
# Build Info
```
2.4.3
```