nxp: Finish switch to CONFIG_NXP_ESBC

There are two remaining users of the CONFIG_SECURE_BOOT symbol that have
not been migrated to another symbol.  In this case, they should be using
CONFIG_NXP_ESBC as their guard.

Cc: Vladimir Oltean <olteanv@gmail.com>
Fixes: 5536c3c9d0d1 ("freescale/layerscape: Rename the config CONFIG_SECURE_BOOT name")
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/Makefile b/Makefile
index e3c18d8..37964a8 100644
--- a/Makefile
+++ b/Makefile
@@ -887,7 +887,7 @@
 ifeq ($(CONFIG_SPL_FSL_PBL),y)
 ALL-$(CONFIG_RAMBOOT_PBL) += u-boot-with-spl-pbl.bin
 else
-ifneq ($(CONFIG_SECURE_BOOT), y)
+ifneq ($(CONFIG_NXP_ESBC), y)
 # For Secure Boot The Image needs to be signed and Header must also
 # be included. So The image has to be built explicitly
 ALL-$(CONFIG_RAMBOOT_PBL) += u-boot.pbl