st/nine: Enable multisampling also without depth buffer

Found with wine tests.

Signed-off-by: Axel Davy <davyaxel0@gmail.com>
Acked-by: Timur Kristóf <timur.kristof@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/10160>

src/gallium/frontends/nine/nine_state.c

@@ -346,7 +346,7 @@ static inline DWORD
 check_multisample(struct NineDevice9 *device)
 {
     DWORD *rs = device->context.rs;
-    DWORD new_value = (rs[D3DRS_ZENABLE] || rs[D3DRS_STENCILENABLE]) &&
+    DWORD new_value = device->context.rt[0] &&
                       device->context.rt[0]->desc.MultiSampleType >= 1 &&
                       rs[D3DRS_MULTISAMPLEANTIALIAS];
     if (rs[NINED3DRS_MULTISAMPLE] != new_value) {