[submodule] Update submodule sonic-linux-kernel to the latest HEAD automatically (#15782)

#### Why I did it
src/sonic-linux-kernel
```
* d070cae - (HEAD -> master, origin/master, origin/HEAD) arm64: dts: marvell: Add Nokia 7215-IXS-A1 board (#321) (34 hours ago) [Pavan-Nokia]
```
#### How I did it
#### How to verify it
#### Description for the changelog

Author: mssonicbld