msm: hotplug: remove code related to cpu_killed

Earlier the completion event cpu_killed was used to synchronize
notify to hot plug framework that the CPU is dead. But now it is
replaced with another completion event cpu_died and it is placed
in the hotplug framework itself. So there is no need for a
platform to implement a completion event.

But in msm platform driver the completion event related code
was not removed with the changes in hotplug framework. This
patch removes the unused code.

Signed-off-by: Venkat Devarasetty <vdevaras@codeaurora.org>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>

Conflicts:
	arch/arm/mach-msm/hotplug.c