Do not call dma_buf_set_priority().

No mainline kernel has it, so the module fails to build. The comment above
the call says it changes no functional behaviour of the driver: it only makes
the priority visible to other tools through fdinfo.

--- a/greenboost.c
+++ b/greenboost.c
@@ -966,8 +966,10 @@
  * that, nothing to call here for them. */
 static void gb_apply_priority_hint(struct dma_buf *dmabuf, u32 alloc_flags)
 {
-	if (alloc_flags & (GB_ALLOC_KV_CACHE | GB_ALLOC_T1_PRIORITY))
-		dma_buf_set_priority(dmabuf, 200); /* DEFAULT=128, MAX=255; comfortably "keep longer" */
+	/* dma_buf_set_priority() is not in mainline. Upstream notes above that
+	 * the call changes no functional behaviour, so skip it. */
+	(void)dmabuf;
+	(void)alloc_flags;
 }
 
 /* ------------------------------------------------------------------ */