intrabc: fix mismatch
intrabc: fix mismatch

The "txb_split_count" counter should be properly updated.

BUG=aomedia:864

Change-Id: I3fb34a818c3f474085c4a2980a2d3b68bd33fb12

GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom