s390x/css: fix cc handling for XSCH

The function ioinst_handle_xsch is presenting cc 2 when it's supposed to
present cc 1 and the other way around, because css_do_xsch has the error
codes mixed up. Because cc 1 has precedence over cc 2 we also have to
swap the two checks.

Let us fix this.

Signed-off-by: Halil Pasic <pasic@linux.vnet.ibm.com>
Reported-by: Pierre Morel <pmorel@linux.vnet.ibm.com>
Message-Id: <20170831121828.85885-1-pasic@linux.vnet.ibm.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
