megasas: Legacy command line handling fix

megasas: Legacy command line handling fix

Only apply legacy command line handling when the device has not been
hot-plugged. Propagate failure of legacy command line handling.

Cc: qemu-stable@nongnu.org
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>
(cherry picked from commit 22d6aa03fd87ba5f219d26bc1810646d0f95842a)

Conflicts:

	hw/scsi/megasas.c

* modified to avoid dependency on fancy new upcast macros

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>