s390/ap: Remove ap device suspend and resume callbacks

With the removal of the s390 hibernate support the suspend and
resume callbacks for the ap devices are not needed any more.

This patch removes the callbacks and the ap bus' registration
struct for the power management.

Signed-off-by: Harald Freudenberger <freude@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>