smegw01: Fix inverted CONFIG_SYS_BOOT_LOCKED logic

CONFIG_SYS_BOOT_LOCKED means that a restricted boot environment will
be used. In this case, hab_auth_img_or_fail should be called to prevent
U-Boot to continue running when the fitImage authentication fails.

Fix the logic accordingly.

Additionally, select CONFIG_SYS_BOOT_LOCKED by default.

Signed-off-by: Eduard Strehlau <eduard@lionizers.com>
Signed-off-by: Fabio Estevam <festevam@denx.de>