s390/sclp_sdias: fix sclp_sdias_copy() virtual vs physical address confusion

Due to historical reasons sclp_sdias_copy() misuses
the notion of physical vs virtual addresses difference.

Note: this does not fix a bug currently, since virtual
and physical addresses are identical.

Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>