colibri_imx7_emmc: enable CONFIG_ARMV7_BOOT_SEC_DEFAULT

colibri_imx7_emmc: enable CONFIG_ARMV7_BOOT_SEC_DEFAULT

Enable CONFIG_ARMV7_BOOT_SEC_DEFAULT by default to avoid a kernel
crash when booting NXP linux kernels in non-secure world,
when job ring device allocation is done by CAAM hw accelerator driver:

caam 30900000.caam: job rings = 3, qi = 0
caam_jr 30901000.jr0: failed to flush job ring 0
caam_jr: probe of 30901000.jr0 failed with error -5
caam_jr 30902000.jr1: failed to flush job ring 1
caam_jr: probe of 30902000.jr1 failed with error -5
caam_jr 30903000.jr2: failed to flush job ring 2
caam_jr: probe of 30903000.jr2 failed with error -5
caam algorithms registered in /proc/crypto
Job Ring Device allocation for transform failed
caam 30900000.caam: caam pkc algorithms registered in /proc/crypto
Unable to handle kernel NULL pointer dereference at virtual address 00000010
pgd = c0004000
[00000010] *pgd=00000000
Internal error: Oops: 5 [#1] PREEMPT SMP ARM
Modules linked in:
CPU: 0 PID: 1 Comm: swapper/0 Tainted:
Hardware name: Freescale i.MX7 Dual (Device Tree)
task: ec0d8000 task.stack: ec0ce000
PC is at caam_sm_startup+0x3f8/0x4f4

Signed-off-by: Igor Opaniuk <igor.opaniuk@toradex.com>