mx7dsabresd_secure_defconfig: Use CONFIG_ARMV7_BOOT_SEC_DEFAULT

There is no need for introducing MX7_SEC, as there is the
CONFIG_ARMV7_BOOT_SEC_DEFAULT option for this purpose.

Switch to CONFIG_ARMV7_BOOT_SEC_DEFAULT and get rid of
MX7_SEC.

Tested by booting a 4.1.15 NXP kernel with mx7dsabresd_secure_defconfig
target.

Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
Acked-by: Stefan Agner <stefan.agner@toradex.com>
diff --git a/arch/arm/imx-common/Kconfig b/arch/arm/imx-common/Kconfig
index c6b38bc..1b7da5a 100644
--- a/arch/arm/imx-common/Kconfig
+++ b/arch/arm/imx-common/Kconfig
@@ -17,12 +17,3 @@
 	depends on ARCH_MX7 || ARCH_MX6
 	help
 	  bootaux [addr] to boot auxiliary core.
-
-config MX7_SEC
-	bool "Support booting MX7 in secure mode"
-	depends on ARCH_MX7
-	help
-	  NXP kernel requires to boot MX7 in secure mode. Select
-	  this options if you want to boot a NXP kernel. In order
-	  to boot a mainline kernel this option needs to be
-	  unselected.
diff --git a/configs/mx7dsabresd_secure_defconfig b/configs/mx7dsabresd_secure_defconfig
index 0a3930e..aa92a38 100644
--- a/configs/mx7dsabresd_secure_defconfig
+++ b/configs/mx7dsabresd_secure_defconfig
@@ -38,4 +38,4 @@
 CONFIG_G_DNL_VENDOR_NUM=0x0525
 CONFIG_G_DNL_PRODUCT_NUM=0xa4a5
 CONFIG_OF_LIBFDT=y
-CONFIG_MX7_SEC=y
+CONFIG_ARMV7_BOOT_SEC_DEFAULT=y