Martin Storsjö authored Aug 13, 2015 and Henrik Gramner committed Oct 11, 2015

This gets rid of a few unnecessary (and confusing) steps in
calculating the increment to i00.

checkasm timing      Cortex-A7    A8    A9
intra_predict_8x8c_p_c      5525  4732  4755
intra_predict_8x8c_p_neon   1719  1140  1262  (before)
intra_predict_8x8c_p_neon   1663  1142  1255  (after)