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: NFabio Estevam <fabio.estevam@nxp.com>
Acked-by: NStefan Agner <stefan.agner@toradex.com>

arch/arm/imx-common/Kconfig

@@ -17,12 +17,3 @@ config IMX_BOOTAUX
 	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.

configs/mx7dsabresd_secure_defconfig

@@ -38,4 +38,4 @@ CONFIG_G_DNL_MANUFACTURER="FSL"
 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