We neglect to check the return value of xenbus_register_backend
and take actions when that fails. This patch fixes that and adds
code to deal with those type of failures.
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: NJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>