passthrough: Fix PCI hot-plug option parsing

When a PCI function is passed-through extra options may be passed
through.
In the case of boot-time PCI pass-through the documented format is:
    [dom:]bus:dev.slot[@vslot][[,opt]...]
    e.g.
    00:01.00.1@7,msitranslate=3D1

In the case of PCI hot-plug the xm pci-attach command take the
following arguments:
    [-o opt[,opt]...] [dom:]bus:dev.slot [vslot]
    e.g.
    -o msitranslate=3D1 00:01.00.1 7

    These xm ends up passing these to xem-qemu as:
    [dom:]bus:dev.slot[[,opt]...][@vslot]
    e.g.
    00:01.00.1,msitranslate=3D1@7

    Note that the option and the vslot have are transposed when
    compared to the format used by boot-time PCI pass-through.

The parser inside qemu-xen can only handle the format used by
boot-time PCI pass-through and because of this ignores
any options passed by hot-plug.

This patch alters format used by hot-plug to match the parser.

Signed-off-by: Simon Horman <horms@verge.net.au>

tools/python/xen/xend/XendDomainInfo.py

@@ -706,12 +706,12 @@ class XendDomainInfo:
                 config_opts = map(lambda (x, y): x+'='+y, config_opts)
                 opts = ',' + reduce(lambda x, y: x+','+y, config_opts)
 
-            bdf_str = "%s:%s:%s.%s%s@%s" % (new_dev['domain'],
+            bdf_str = "%s:%s:%s.%s@%s%s" % (new_dev['domain'],
                 new_dev['bus'],
                 new_dev['slot'],
                 new_dev['func'],
-                opts,
-                new_dev['vslot'])
+                new_dev['vslot'],
+                opts)
             self.image.signalDeviceModel('pci-ins', 'pci-inserted', bdf_str)
 
             vslot = xstransact.Read("/local/domain/0/device-model/%i/parameter"