imx: configs: Cleanup CONFIG_SECURE_BOOT comments

Since commit 6e1f4d2652e7 ("arm: imx-common: add SECURE_BOOT option
to Kconfig") the SECURE_BOOT option is selected through Kconfig.

Cleanup comments in code to align with this change.

Signed-off-by: Breno Lima <breno.lima@nxp.com>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
diff --git a/include/configs/cl-som-imx7.h b/include/configs/cl-som-imx7.h
index 06f987d..d0a60c2 100644
--- a/include/configs/cl-som-imx7.h
+++ b/include/configs/cl-som-imx7.h
@@ -17,9 +17,6 @@
 
 #define CONFIG_BOARD_LATE_INIT
 
-/* Uncomment to enable secure boot support */
-/* #define CONFIG_SECURE_BOOT */
-
 /* Network */
 #define CONFIG_FEC_MXC
 #define CONFIG_FEC_XCV_TYPE             RGMII
diff --git a/include/configs/mx7ulp_evk.h b/include/configs/mx7ulp_evk.h
index 8964dcd..3b02362 100644
--- a/include/configs/mx7ulp_evk.h
+++ b/include/configs/mx7ulp_evk.h
@@ -11,9 +11,6 @@
 #include <linux/sizes.h>
 #include <asm/arch/imx-regs.h>
 
-/*Uncomment it to use secure boot*/
-/*#define CONFIG_SECURE_BOOT*/
-
 #define CONFIG_BOARD_POSTCLK_INIT
 #define CONFIG_SYS_BOOTM_LEN		0x1000000