s390/cio: fix intparm documentation

The common I/O layer is maintaining an "intparm" inspired by
the hardware intparm for driver usage. This "intparm" is not
only applicaple for ssch, but also for hsch/csch. The kerneldoc
states that it is only updated for hsch/csch if no prior request
is pending; however, this is not what the code does (whether
that would actually desireable is a different issue.)

Let's at least fix the kerneldoc for now.

Fixes: b2ffd8e9 ("[S390] cio: Add docbook comments.")
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Sebastian Ott <sebott@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>