server: avoid unneeded recursion in dispatch_vdi_port_data
server: avoid unneeded recursion in dispatch_vdi_port_data

dispatch_vdi_port_data, was calling vdi_read_buf_release when no client
is connected to free the passed in buf. The only difference between
vdi_read_buf_release and directly adding the buffer back to the ring
with ring_add, is that vdi_read_buf_release calls read_from_vdi_port
after adding the buffer back. But dispatch_vdi_port_data only gets called
from read_from_vdi_port itself, thus this would lead to recursing into
read_from_vdi_port. read_from_vdi_port is protected against recursion and
will immediately return if called recursively. Thus calling
vdi_read_buf_release from dispatch_vdi_port_data is pointless, instead
simply putting the buffer back in the ring suffices.

fgouget/spice,fgouget/spice,elmarco/spice,alon/spice-server,alon/spice-server,elmarco/spice,fgouget/spice,freedesktop-unofficial-mirror/spice__spice,mathslinux/spice,mathslinux/spice,elmarco/spice,dezelin/spice,mathslinux/spice,dezelin/spice,dezelin/spice,SPICE/spice,mathslinux/spice,ya-mouse/spice,freedesktop-unofficial-mirror/spice__spice,mathslinux/spice,fgouget/spice,dezelin/spice,elmarco/spice,Fantu/spice,elmarco/spice,alon/spice-server,ya-mouse/spice,freedesktop-unofficial-mirror/spice__spice,freedesktop-unofficial-mirror/spice__spice,freedesktop-unofficial-mirror/spice__spice,Fantu/spice,ya-mouse/spice,dezelin/spice,SPICE/spice,alon/spice-server,SPICE/spice,Fantu/spice,Fantu/spice,alon/spice-server