[submodule] Update submodule sonic-linux-kernel to the latest HEAD au…

…tomatically (sonic-net#19719)

#### Why I did it
src/sonic-linux-kernel
```
* b9ac5dd - (HEAD -> master, origin/master, origin/HEAD) [Micas] Enable CONFIG_SENSORS_ISL68137 and CONFIG_SENSORS_INA3221 (sonic-net#417) (4 hours ago) [Philo]
```
#### How I did it
#### How to verify it
#### Description for the changelog