devenum: Constify a variable

[Andrew Talbot]

Changelog:
    devenum: Constify a variable.

diff -urN a/dlls/devenum/factory.c b/dlls/devenum/factory.c
--- a/dlls/devenum/factory.c	2006-05-23 13:47:50.000000000 +0100
+++ b/dlls/devenum/factory.c	2007-04-21 11:48:36.000000000 +0100
@@ -82,7 +82,7 @@
  */
 static HRESULT WINAPI DEVENUM_IClassFactory_CreateInstance(
     LPCLASSFACTORY iface,
-    LPUNKNOWN pUnkOuter,
+    const IUnknown *pUnkOuter,
     REFIID riid,
     LPVOID *ppvObj)
 {