releasetools: Fix the expected total blocks.

With the change in [1], it zeroes out extra blocks that might be read
by dm-verity. We should update the expected number of blocks that get
touched.

[1] commit e9b619108dbe0c358ba6c14e27c92a623a7c1059.

Bug: 23786644
Change-Id: I7a7c3531e5af6bf381d3a14832e77abfa9a8efce
1 file changed