warp: Use the correct symbol for CONFIG_IMX_HAB

The intention of commit d714a75f ("imx: replace CONFIG_SECURE_BOOT
with CONFIG_IMX_HAB") was to convert from CONFIG_SECURE_BOOT to
CONFIG_IMX_HAB, but it replaced with an extra "_" character.

Fix it by using the correct CONFIG_IMX_HAB symbol.

Fixes: d714a75f ("imx: replace CONFIG_SECURE_BOOT with CONFIG_IMX_HAB")
Signed-off-by: Fabio Estevam <festevam@gmail.com>