freescale/layerscape: Rename the config CONFIG_SECURE_BOOT name

Rename CONFIG_SECURE_BOOT to CONFIG_NXP_ESBC to avoid conflict
with UEFI secure boot.

Signed-off-by: Udit Agarwal <udit.agarwal@nxp.com>
Signed-off-by: Priyanka Jain <priyanka.jain@nxp.com>
diff --git a/board/freescale/common/Makefile b/board/freescale/common/Makefile
index a9d61a8..b0e109f 100644
--- a/board/freescale/common/Makefile
+++ b/board/freescale/common/Makefile
@@ -75,7 +75,7 @@
 
 obj-$(CONFIG_LAYERSCAPE_NS_ACCESS)	+= ns_access.o
 
-ifdef CONFIG_SECURE_BOOT
+ifdef CONFIG_NXP_ESBC
 obj-$(CONFIG_CMD_ESBC_VALIDATE) += fsl_validate.o cmd_esbc_validate.o
 endif
 obj-$(CONFIG_CHAIN_OF_TRUST) += fsl_chain_of_trust.o