ioemu: error checkin when setting up the Cirrus Logic video device.

ioemu: error checkin when setting up the Cirrus Logic video device.

set_mm_mapping() may fail because of xc_domain_populate_physmap().  In
this case, we should not blindly go on; the xc_map_foreign_batch()
that follows will cause a page fault and, at best, get mapped in a
zeroed page from the dom0 (which is not what we want).  While I'm in
here, fix a memory leak on an error path.

Signed-off-by: Chris Lalancette <clalance@redhat.com>