This function includes a number of explicit fprintf()s for errors.
Change these to use error_report() instead.

Also replace the single exit(EXIT_FAILURE) with an explicit exit(1), since
the latter is the more usual idiom in qemu by a large margin.
Signed-off-by: NDavid Gibson <david@gibson.dropbear.id.au>
Reviewed-by: NAlexey Kardashevskiy <aik@ozlabs.ru>
Reviewed-by: NMarkus Armbruster <armbru@redhat.com>