hikey-kernel: Update prebuilt kernel to 469ab8e am: 812e3d9
am: 3f21d3a

* commit '3f21d3a469ea0a6b983d5336bd09fccbc103e54b':
  hikey-kernel: Update prebuilt kernel to 469ab8e

Change-Id: I3bcb7338bb5d678a3face34ccb7761f5cf7162e8