[submodule] Update submodule sonic-linux-kernel to the latest HEAD automatically (#19201)

#### Why I did it
src/sonic-linux-kernel
```
* f9bfb90 - (HEAD -> master, origin/master, origin/HEAD) [ci] Migrate to sonicbld1es agent pool. (#397) (15 minutes ago) [Liu Shilong]
```
#### How I did it
#### How to verify it
#### Description for the changelog

Author: mssonicbld