Consolidate 2 two pass partition search speed features

Consolidated 2 two pass partition search speed features to make it
simple.

BUG=aomedia:2324

Change-Id: Id1384c85a9cf4bcd1b0d1f6e293840f0afb907d3
diff --git a/av1/encoder/block.h b/av1/encoder/block.h
index 7221cfb..2458698 100644
--- a/av1/encoder/block.h
+++ b/av1/encoder/block.h
@@ -155,7 +155,7 @@
 
 // Region size for mode decision sampling in the first pass of partition
 // search(two_pass_partition_search speed feature), in units of mi size(4).
-// Used by the mode_pruning_based_on_two_pass_partition_search speed feature.
+// Used by the mode pruning in two_pass_partition_search feature.
 #define FIRST_PARTITION_PASS_SAMPLE_REGION 8
 #define FIRST_PARTITION_PASS_SAMPLE_REGION_LOG2 3
 #define FIRST_PARTITION_PASS_STATS_TABLES                     \