arm: imx: hab: Make authenticate_image() return zero on open boards

arm: imx: hab: Make authenticate_image() return zero on open boards

The BootROM will not successfully process a HAB image passed by u-boot
unless the board has been set into locked mode. Some of the existing usages
of authenticate_image() expect and rely on unlocked boards doing the
following

1. Not calling into the BootROM authenticate_image() callback
2. Returning a pass status for authenticate_image() calls anyway

A previous patch removed the necessity to call into imx_hab_is_enabled()
twice. This patch ensures the reliance on authenticate_image() returning
zero is maintained.

Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Suggested-by: Breno Matheus Lima <brenomatheus@gmail.com>
Cc: Stefano Babic <sbabic@denx.de>
Cc: Fabio Estevam <fabio.estevam@nxp.com>
Cc: Peng Fan <peng.fan@nxp.com>
Cc: Albert Aribaud <albert.u.boot@aribaud.net>
Cc: Sven Ebenfeld <sven.ebenfeld@gmail.com>
Cc: George McCollister <george.mccollister@gmail.com>
Tested-by: Breno Lima <breno.lima@nxp.com>