[S390] chsc: initialization fixes

This patch fixes:
 * kfree vs. free_page usage
 * structure definition for determine_css_characteristics
 * naming convention for the chsc init function
 * deregistration of crw handlers in the cleanup path

Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>