[submodule]: update linux kernel module

* 652f259 2018-10-01 | [Kernel] fix kernel build errors (#65) (HEAD, origin/201803) [Ying Xie]
* 55c7a19 2018-10-01 | uart: fix race between uart_put_char() and uart_shutdown() (#64) [lguohan]

Signed-off-by: Guohan Lu <gulv@microsoft.com>