Revert "hammerhead: update prebuilt kernel"

This reverts commit a36a8be11a10feab39df11c0b8a2eb23cf70e9f6.

Change-Id: Ia286f217ae08bacbe0f6ea7d7382251cd085a6a6
diff --git a/zImage-dtb b/zImage-dtb
index a89fdba..804fb1b 100644
--- a/zImage-dtb
+++ b/zImage-dtb
Binary files differ