app: aboot: add check on size of atags
app: aboot: add check on size of atags

Added check on tags size while updating the atags,
it can cross the max size allowed and overwrite
kernel region.

Change-Id: Id4750f7cd5daa3d5f0d93950bb1a24016adfd9b7

efidroid/lk,efidroid/lk,efidroid/lk,efidroid/lk,efidroid/lk