This hides behind --enable-ext_partition_types_ab. When that flag is
set, the mixed partitions change from

   +-+-+---+          +-+-+---+
   |   |   |          | | |   |
   |---+   |    to    | | |   |
   |   |   |          | | |   |
   +-+-+---+          +-+-+---+

(that's PARTITION_VERT_A; other partitions change similarly).

Since 128x32 and 32x128 block support hasn't yet been merged, this
patch also temporarily disables these partitions for 128x128 blocks.

Change-Id: Ic479c0fc129f590b8ad56d72dc98ba79ae1bd1cf