include: env: ti: Add support for secure firmwares

include: env: ti: Add support for secure firmwares

Secure firmwares must be loaded if SOC is secure,
currently rproc framework chooses non-secure firmware always.

So adding support to load secure firmware, when SOC is secure

Signed-off-by: Manorit Chawdhry <m-chawdhry@ti.com>
Signed-off-by: Udit Kumar <u-kumar1@ti.com>
Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> # Intel Edison
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>