dix: Change AllocMaster into AllocDevicePair, allow creation of SDs too.

Allocating a slave device is essentially the same as allocating a master device.
Hence we rename AllocMaster to AllocDevicePair and provided the ability to
indicate if a master or slave device pair is required.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>

Xi/chdevhier.c

@@ -108,7 +108,7 @@ ProcXChangeDeviceHierarchy(ClientPtr client)
                     strncpy(name, (char*)&c[1], c->namelen);
 
 
-                    rc = AllocMasterDevice(client, name, &ptr, &keybd);
+                    rc = AllocDevicePair(client, name, &ptr, &keybd, TRUE);
                     if (rc != Success)
                     {
                         xfree(name);