ipmi: remove the need of an ending record in the SDR table

Currently, the code initializing the sdr table relies on an ending
record with a recid of 0xffff. This patch changes the loop to use the
sdr size as a breaking condition.

Signed-off-by: Cédric Le Goater <clg@fr.ibm.com>
Acked-by: Corey Minyard <cminyard@mvista.com>
Reviewed-by: Marcel Apfelbaum <marcel@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
