migration/rdma: clean up qemu_rdma_dest_init a bit

Do not check for rdma->host being empty twice.  This removes a large
"if" block, so code indentation is changed.  While at it, remove an
ugly goto from the loop, replacing it with a cleaner if logic.  And
finally, there's no need to initialize `ret' variable since is always
has a value.

Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Tested-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

--

fixed space detected by Dave
Signed-off-by: Juan Quintela <quintela@redhat.com>
