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-imx8mn.c b/drivers/clk/imx/clk-imx8mn.c
index 4048cc6..eb43971 100644
--- a/drivers/clk/imx/clk-imx8mn.c
+++ b/drivers/clk/imx/clk-imx8mn.c
@@ -293,7 +293,7 @@
 	       imx_clk_fixed_factor("sys_pll2_1000m", "sys_pll2_out", 1, 1));
 
 	base = dev_read_addr_ptr(dev);
-	if (base == (void *)FDT_ADDR_T_NONE)
+	if (!base)
 		return -EINVAL;
 
 	clk_dm(IMX8MN_CLK_A53_SRC,