configs: sei510/610: android bootflow via abootimg

Activate the following Kconfig options:
* AVB       for Android Verified Boot support
* ADTIMG    for merging DTBOs
* ABOOTIMG  for extracting Android boot image

Also rework the partitioning tables:
- add a misc partition to handle BCB messages
- add a dtbo partition to store various DTBOs
- add a vbmeta partition for AVB hashes
- Merge vendor and system into the "super" partition

Note: avb support is disables by default. To activate it:
 => setenv force_avb 1;
 => saveenv;

Signed-off-by: Guillaume La Roque <glaroque@baylibre.com>
Signed-off-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
Acked-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>