arm: imx: hab: Print HAB event log only after calling ROM

The current flow of authenticate_image() will print the HAB event log even
if we reject an element of the IVT header before ever calling into the ROM.
This can be confusing.

This patch changes the flow of the code so that the HAB event log is only
printed out if we have called into the ROM and received some sort of status
code.

Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Suggested-by: Cc: 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>
Reviewed-by: Fabio Estevam <fabio.estevam@nxp.com>