[201911][sonic-linux-kernel] submodule update (#11353)

```
23fc702 [201911][patch] mlxsw: i2c: Prevent transaction execution for special chip st (#278)
e4f44e4 [201911] Increase log buf len size to 1M (#265)
ef6abe3 [201911] Apply kernel patches to fix emmc unreliability (#264)
7458347 [201911] Increase log buf len size to 1M
4edf1b4 [201911] Apply kernel patches to fix emmc unreliability
```

Signed-off-by: Stepan Blyschak <[email protected]>

Why I did it
I updated sonic-linux-kernel to pick a fix for a bug happening during ISSU that caused CPU stall.

How I did it
Updated submodule

How to verify it
Build and run warm reboot

Author: stepanblyschak