pata_sc1200: Fix crash on boot

The SC1200 needs a NULL terminator or it may cause a crash on boot.

Bug #14227

Also correct a bogus comment as the driver had serializing added so can run
dual port.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>