There's no need to send in both the address of the subchannel
struct, and an element within it, to populate the ORB.

Pass the whole pointer and let cp_get_orb() take the pieces
that are needed.
Suggested-by: Matthew Rosato <mjrosato@linux.ibm.com>
Signed-off-by: Eric Farman <farman@linux.ibm.com>
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>