s390: remove pm support from console drivers

The power-management functions are unused since the
'commit 39421627 ("s390: remove broken hibernate / power management
support")'. Remove the unsued pm functions from the console drivers.

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