Avoid sending tx type for ext_tx reduced set for sub 8x8
Avoid sending tx type for ext_tx reduced set for sub 8x8

This makes the handling of sub8x8 the same as when the
ext_tx reduced set is turned off.

Change-Id: I3123e473fc70469330bb49d960d02cb1aebc17cf

luctrudeau/aom,smarter/aom,GrokImageCompression/aom,GrokImageCompression/aom,luctrudeau/aom,GrokImageCompression/aom,GrokImageCompression/aom,smarter/aom,smarter/aom,GrokImageCompression/aom,luctrudeau/aom,smarter/aom,GrokImageCompression/aom,luctrudeau/aom,luctrudeau/aom,smarter/aom,smarter/aom,luctrudeau/aom