s390/cio: remove pm support from chsc subchannel driver

As part of removing the broken pm-support from s390 arch, remove
the pm-calls from chsc subchannel driver. The power-management
functions are unused since the 'commit 39421627 ("s390: remove
broken hibernate / power management support")'.

Signed-off-by: Vineeth Vijayan <vneethv@linux.ibm.com>
Reviewed-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>