Fixed mb_skip_coeff bug

When mb_skip_coeff is set, the idct is not necessary.  Prior
to this patch, the code would call idcts based on leftover
eob information.  This patch will now skip the idct for
SPLIT_MV and clear out the eobs for B_PRED, forcing the idct
to be skipped.

Change-Id: If5b0d2ed3ebd07789d30ec5160df927485fcaa17