mtd: nand: mxs: use simpler runtime cpu dection macros

Use simpler runtime cpu dection macros.

Signed-off-by: Peng Fan <van.freenix@gmail.com>
Cc: Stefano Babic <sbabic@denx.de>
Cc: Scott Wood <oss@buserror.net>
diff --git a/drivers/mtd/nand/mxs_nand.c b/drivers/mtd/nand/mxs_nand.c
index b5bbd88..5528d4b 100644
--- a/drivers/mtd/nand/mxs_nand.c
+++ b/drivers/mtd/nand/mxs_nand.c
@@ -152,7 +152,7 @@
 	int max_ecc_strength_supported;
 
 	/* Refer to Chapter 17 for i.MX6DQ, Chapter 18 for i.MX6SX */
-	if (is_cpu_type(MXC_CPU_MX6SX) || is_soc_type(MXC_SOC_MX7))
+	if (is_mx6sx() || is_mx7())
 		max_ecc_strength_supported = 62;
 	else
 		max_ecc_strength_supported = 40;