zink: always insert current batch sparse semaphore into sparse wait chain

this avoids desync in the case where a batch performs multiple distinct
sparse commit operations

cc: mesa-stable

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/35978>
diff --git a/src/gallium/drivers/zink/zink_bo.c b/src/gallium/drivers/zink/zink_bo.c
index 21a0191..be67b2c 100644
--- a/src/gallium/drivers/zink/zink_bo.c
+++ b/src/gallium/drivers/zink/zink_bo.c
@@ -805,7 +805,7 @@
 
    uint32_t va_page = offset / ZINK_SPARSE_BUFFER_PAGE_SIZE;
    uint32_t end_va_page = va_page + DIV_ROUND_UP(size, ZINK_SPARSE_BUFFER_PAGE_SIZE);
-   VkSemaphore cur_sem = VK_NULL_HANDLE;
+   VkSemaphore cur_sem = *sem;
    if (commit) {
       while (va_page < end_va_page) {
          uint32_t span_va_page;