zephyr-kernel: upgrade 2.7.0 -> 2.7.1

Zephyr 2.7.1 release notes:
https://github.com/zephyrproject-rtos/zephyr/releases/tag/zephyr-v2.7.1



Signed-off-by: JingHuiTham <jing.hui.tham@intel.com>
Signed-off-by: Naveen Saini <naveen.kumar.saini@intel.com>