MT#60284 Only check whether /dev/virtio-ports/org.qemu.guest_agent.0 exists

/dev/virtio-ports/org.qemu.guest_agent.0 usually is a symlink to the
character device /dev/vport1p1. So adjust the device check accordingly
and only verify it exists, but don't expected any special file type.
This actually matches the behavior we also have in ngcp-installer.

Fixup for commit 82e6638b40

Change-Id: I0aa93c1f0e1086847eb7ed6967692a52e183bdc3
(cherry picked from commit 4a292ab4be)
(cherry picked from commit e67a8fa200)

templates/scripts/includes/deployment.sh

@@ -1536,7 +1536,8 @@ echo "Host IP: $(ip-screen)"
 echo "Deployment version: $SCRIPT_VERSION"
 
 # MT#60284 ensure qemu-guest-agent is running if it's available in VM
-if [ -S /dev/virtio-ports/org.qemu.guest_agent.0 ] ; then
+if [ -e /dev/virtio-ports/org.qemu.guest_agent.0 ] ; then
+  echo "Guest Agent VirtIO device detected, starting qemu-guest-agent service"
   systemctl start qemu-guest-agent
 fi