st/nine: Always return OK on SetSoftwareVertexProcessing

This would need more tests to know exactly
if INVALIDCALL can be returned in some
situations.
It seems some games expect D3D_OK,
even when noop and illegal.

Fixes:
#302
#338

Signed-off-by: Axel Davy <davyaxel0@gmail.com>

src/gallium/state_trackers/nine/device9.c

@@ -2728,7 +2728,7 @@ NineDevice9_SetSoftwareVertexProcessing( struct NineDevice9 *This,
         nine_context_set_swvp(This, bSoftware);
         return D3D_OK;
     } else
-        return D3DERR_INVALIDCALL; /* msdn. TODO: check in practice */
+        return D3D_OK; /* msdn seems to indicate INVALIDCALL, but at least Halo expects OK */
 }
 
 BOOL NINE_WINAPI