s390/idle: Remove idle time and count sysfs files

s390/idle: Remove idle time and count sysfs files

Remove the s390 specific idle_time_us and idle_count per cpu sysfs
files. They do not provide any additional value. The risk that there
are existing applications which rely on these architecture specific
files should be very low.

However if it turns out such applications exist, this can be easily
reverted.

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Acked-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>