clk: Fix error checking of dev_read_addr_ptr

dev_read_addr_ptr returns NULL on error, not FDT_ADDR_T_NONE.

Signed-off-by: Sean Anderson <seanga2@gmail.com>
diff --git a/drivers/clk/imx/clk-imx6q.c b/drivers/clk/imx/clk-imx6q.c
index 5ae4781..bd0d3e4 100644
--- a/drivers/clk/imx/clk-imx6q.c
+++ b/drivers/clk/imx/clk-imx6q.c
@@ -115,7 +115,7 @@
 
 	/* CCM clocks */
 	base = dev_read_addr_ptr(dev);
-	if (base == (void *)FDT_ADDR_T_NONE)
+	if (!base)
 		return -EINVAL;
 
 	clk_dm(IMX6QDL_CLK_USDHC1_SEL,