Fix mismtach with ref-mv and ext-partition-types

Change the list of search offsets searched when ext-partition-types
is on for square block_sizes. This is because the VERTICAL_A and
HORIZONTAL_A partitions are incompatible with the default list.

BUG=AOMEDIA:141

Change-Id: I884c45c3d11039b7dcb72336a928362f926473ed
1 file changed