The frame mi has an 1 row and 1 column offset from the beginning of
the allocated memory.
cm->mi = cm->mip + cm->mi_stride + 1;
This offset can be removed. This doesn't change the bitstream.

Also, fixed 1 bug in first_pass code to update xd->mi for each block.

Change-Id: I2327aaadc62d2b00baa5a3c5135281d7fc864ed7