restapi: set domain for vm-init

Wrong check for setting domain for VM

Change-Id: Ia3ee9738b4003b1e094d59a21313f6f84e73ce7f
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1069201
Signed-off-by: Shahar Havivi <shaharh@redhat.com>