arm: imx: hab: Only call ROM once headers are verified

arm: imx: hab: Only call ROM once headers are verified

Previous patches added IVT header verification steps. We shouldn't call
hab_rvt_entry() until we have done the basic header verification steps.

This patch changes the time we make the hab_rvt_entry() call so that it
only takes place if we are happy with the IVT header sanity checks.

Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
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>
Cc: Breno Matheus Lima <brenomatheus@gmail.com>
Tested-by: Breno Lima <breno.lima@nxp.com>
Reviewed-by: Fabio Estevam <fabio.estevam@nxp.com>