refactor(measured boot): move image measurement to generic layer

Right now, the assumption is that the platform post-load hook takes
care of measuring the image that just got loaded. This is how it's
implemented on FVP.

This patch moves the measurement into the generic code
instead. load_auth_image() now calls plat_mboot_measure_image(),
which is a new platform interface introduced in this patch to measure
an image. This is called just after authenticating the image.

Implement plat_mboot_measure_image() for the Arm FVP platform. The code
is copied straight from the post-load hook.

As a result, the FVP specific implementation of
arm_bl2_plat_handle_post_image_load() is no longer needed. We can go
back to using the Arm generic implementation of it.

Change-Id: I7b4b8d28941a865e10af9d0eadaf2e4850942090
Signed-off-by: Sandrine Bailleux <sandrine.bailleux@arm.com>
Signed-off-by: Manish V Badarkhe <Manish.Badarkhe@arm.com>
4 files changed