[submodule] Update submodule sonic-linux-kernel to the latest HEAD automatically (#16283)

#### Why I did it
src/sonic-linux-kernel
```
* a2aa335 - (HEAD -> master, origin/master, origin/HEAD) PATCH] net: allow user to set metric on default route learned via Router Advertisement (#326) (12 hours ago) [abdosi]
```
#### How I did it
#### How to verify it
#### Description for the changelog
This commit is contained in:
mssonicbld 2023-08-25 16:32:30 +08:00 committed by GitHub
parent 618bddc07d
commit e9abf9e5ee
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@ -1 +1 @@
Subproject commit e72818fcb6c2b02864e66d842d67e13d8b67df4a Subproject commit a2aa335d16297badeaed01d2ce552338273bba24