vk/wsi: avoid reading uninitialised memory

It will be ignored by x11_swapchain_result() anyway (because reaching
the `fail` label without setting `result` means the swapchain status was
already a hard error), but the compiler still complains about reading
uninitialised memory.

While at it, drop the unused assignment right before returning.

Signed-off-by: Eric Engestrom <eric.engestrom@intel.com>
Reviewed-by: Caio Marcelo de Oliveira Filho <caio.oliveira@intel.com>

src/vulkan/wsi/wsi_common_x11.c

@@ -980,7 +980,7 @@ static void *
 x11_manage_fifo_queues(void *state)
 {
    struct x11_swapchain *chain = state;
-   VkResult result;
+   VkResult result = VK_SUCCESS;
 
    assert(chain->base.present_mode == VK_PRESENT_MODE_FIFO_KHR);
 
@@ -1024,7 +1024,7 @@ x11_manage_fifo_queues(void *state)
    }
 
 fail:
-   result = x11_swapchain_result(chain, result);
+   x11_swapchain_result(chain, result);
    wsi_queue_push(&chain->acquire_queue, UINT32_MAX);
 
    return NULL;