bisection: exit after updating kernel

Exit after running update_kernel.sh as all the following code is
irrelevant to kernels.

BUG=chromium:1042452

TEST=verified locally.

Change-Id: I9d6fc6f6c319c7a825585868978911806f07a629
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/toolchain-utils/+/2053243
Reviewed-by: George Burgess <gbiv@chromium.org>
Reviewed-by: Manoj Gupta <manojgupta@chromium.org>
Tested-by: Jian Cai <jiancai@google.com>
1 file changed