bootable: Read all asserts in case there are more than one

In A/B, the device check isn´t done by the updater script, but using
metadata for it.

Let´s search if the device codename/assert is included in the string.

Change-Id: Ie856ac699aaa83de2b364bc85a510a037d36edf9
Signed-off-by: Hernán Castañón <herna@paranoidandroid.co>
Signed-off-by: theimpulson <aayushgupta219@gmail.com>