init: cleanup panic and coredump

* We should not have two "write apanic_console", or the phone always hang
after a panic.
* Coredump doesn't exists.
* Copy last_kmsg to start of post-fs-data
* Lockup detector is disabled in kernel, remove.

Change-Id: Idd875c2f7450c4526eb80df645b8e0499607725a