tools/hotplug/NetBSD: update netbsd scripts (interface names)

sysctl fail due to the '.' in the interface name:

Jan 10 00:02:26 paris /netbsd: xvif108.0: could not attach sysctl nodes
Jan 10 00:02:57 paris /netbsd: sysctl_createv: sysctl_create(xvif108.0)
returned 22

The kernel driver have recently been fixed and attached patch updates
to the hotplug scripts accordingly.

Signed-off-by: Christoph Egger <Christoph.Egger@amd.com>
Committed-by: Ian Jackson <ian.jackson@eu.citrix.com>

tools/hotplug/NetBSD/vif-bridge

@@ -23,7 +23,7 @@ case $xstatus in
 	xbridge=$(xenstore-read "$xpath/bridge")
 	xfid=$(xenstore-read "$xpath/frontend-id")
 	xhandle=$(xenstore-read "$xpath/handle")
-	iface=xvif$xfid.$xhandle
+	iface=$(xenstore-read "$xpath/vifname")
 	echo ifconfig $iface up
 	ifconfig $iface up
 	brconfig $xbridge add $iface

tools/hotplug/NetBSD/vif-ip

@@ -23,7 +23,7 @@ case $xstatus in
 	xip=$(xenstore-read "$xpath/ip")
 	xfid=$(xenstore-read "$xpath/frontend-id")
 	xhandle=$(xenstore-read "$xpath/handle")
-	iface=xvif$xfid.$xhandle
+	iface=$(xenstore-read "$xpath/vifname")
 	echo ifconfig $iface $xip up
 	ifconfig $iface $xip up
 	xenstore-write $xpath/hotplug-status connected