bootanimation: Remove a property_set that is causing a warning in dmesg. DO NOT MERGE

Remove a property_set() call that causes the kernel error log:

<3>[   36.437164] init: sys_prop: permission denied uid:1003  name:service.bootanim.exit

This set fails because the property is read only for non-root processes.
It was added by Kevin as part of the clean exit of the boot animation
change, but it's only needed when testing the boot animation from cmdline.
When called from init, init will clear the property itself before it
reruns the boot animation.

Change-Id: I07563009f57d576da8063708cbe66ff08f6757c8
Signed-off-by: Mike J. Chen <mjchen@google.com>