IB/srpt: Modify a debug statement

Since a later patch will remove ib_device.dma_device and since knowing
the value of that pointer is not too important, remove dma_device from
the debug output.

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>