cleanup: change the _end in compressed vmlinux_64.lds.

also change _heap to _ebss that is not needed.
Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>