armv7: ls102xa: Increase the supported kernel size

Increase the kernel size supported for LS1021A platform. Define
CONFIG_SYS_BOOTM_LEN to 64M.

Signed-off-by: Alison Wang <alison.wang@nxp.com>
Reviewed-by: York Sun <york.sun@nxp.com>
diff --git a/include/configs/ls1021atwr.h b/include/configs/ls1021atwr.h
index f820de3..ae58646 100644
--- a/include/configs/ls1021atwr.h
+++ b/include/configs/ls1021atwr.h
@@ -523,5 +523,6 @@
 #endif
 
 #include <asm/fsl_secure_boot.h>
+#define CONFIG_SYS_BOOTM_LEN	(64 << 20) /* Increase max gunzip size */
 
 #endif