Remove an obsolete ToDo

BUG=aomedia:2616

Change-Id: I7e2c6fc3282d3ff4bf96cfbf810e212315e68c05

aom_dsp/prob.h

diff --git a/aom_dsp/prob.h b/aom_dsp/prob.h
index 20ffdea..ea5e4cb 100644
--- a/aom_dsp/prob.h
+++ b/aom_dsp/prob.h
@@ -26,7 +26,6 @@
 extern "C" {
 #endif
 
-// TODO(negge): Rename this aom_prob once we remove vpxbool.
 typedef uint16_t aom_cdf_prob;
 
 #define CDF_SIZE(x) ((x) + 1)