ramips: hsdma-mtk: fix build on 5.15 kernel

In the 5.15 kernel, we use the staging driver version instead of the
downstream file.

Fixes: 88d982e3bd87 ("ramips: 6.1: mt7621-dma: add hsdma driver to files")
Signed-off-by: Shiji Yang <[email protected]>

target/linux/ramips/modules.mk

@@ -101,7 +101,8 @@ define KernelPackage/hsdma-mtk
 	CONFIG_MTK_HSDMA
   FILES:= \
 	$(LINUX_DIR)/drivers/dma/virt-dma.ko \
-	$(LINUX_DIR)/drivers/dma/mediatek/hsdma-mt7621.ko
+	$(LINUX_DIR)/drivers/staging/mt7621-dma/[email protected] \
+	$(LINUX_DIR)/drivers/dma/mediatek/[email protected]
   AUTOLOAD:=$(call AutoLoad,53,hsdma-mt7621)
 endef