st/nine: Clean GetPrivateData

Move the assert to return error codes in the correct order.
Always set the pSizeOfData to the required buffer size.
Fixes failing wine test device.c test_private_data()

Reviewed-by: Axel Davy <axel.davy@ens.fr>
Signed-off-by: Patrick Rudolph <siro@das-labor.org>

src/gallium/state_trackers/nine/resource9.c

@@ -161,20 +161,22 @@ NineResource9_GetPrivateData( struct NineResource9 *This,
                               DWORD *pSizeOfData )
 {
     struct pheader *header;
+    DWORD sizeofdata;
 
     DBG("This=%p refguid=%p pData=%p pSizeOfData=%p\n",
         This, refguid, pData, pSizeOfData);
 
-    user_assert(pSizeOfData, E_POINTER);
-
     header = util_hash_table_get(This->pdata, refguid);
     if (!header) { return D3DERR_NOTFOUND; }
 
+    user_assert(pSizeOfData, E_POINTER);
+    sizeofdata = *pSizeOfData;
+    *pSizeOfData = header->size;
+
     if (!pData) {
-        *pSizeOfData = header->size;
         return D3D_OK;
     }
-    if (*pSizeOfData < header->size) {
+    if (sizeofdata < header->size) {
         return D3DERR_MOREDATA;
     }