mtd: nand: sunxi: disable clks on device removal

mod and ahb clocks are not disabled when the NAND controller device is
removed.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
diff --git a/drivers/mtd/nand/sunxi_nand.c b/drivers/mtd/nand/sunxi_nand.c
index f8b3a72..cad20fb 100644
--- a/drivers/mtd/nand/sunxi_nand.c
+++ b/drivers/mtd/nand/sunxi_nand.c
@@ -1845,6 +1845,8 @@
 	struct sunxi_nfc *nfc = platform_get_drvdata(pdev);
 
 	sunxi_nand_chips_cleanup(nfc);
+	clk_disable_unprepare(nfc->mod_clk);
+	clk_disable_unprepare(nfc->ahb_clk);
 
 	return 0;
 }