Properly detect VMDK with internal version 2

Initially proposed as [1], but then changed to comment fix only.  VMDK
can have internal version set to 2 when there are few features added
which do not affect us.  Thanks to Jan's commit a1ee8e18 this can be
easily fixed by adding it to list of supported versions.

[1] http://www.redhat.com/archives/libvir-list/2013-June/msg00419.html

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=836676

src/util/virstoragefile.c

@@ -213,7 +213,7 @@ static struct FileTypeInfo const fileTypeInfo[] = {
     },
     [VIR_STORAGE_FILE_VMDK] = {
         0, "KDMV", NULL,
-        LV_LITTLE_ENDIAN, 4, {1},
+        LV_LITTLE_ENDIAN, 4, {1, 2},
         4+4+4, 8, 512, -1, vmdk4GetBackingStore, NULL
     },
     [VIR_STORAGE_FILE_VPC] = {