vp9_encoder.c: remove unused macro

SHARP_FILTER_QTHRESH

unused since:
5373119 Merging in the Switchable interp experiment

Change-Id: I9ccc1883828babffd1886810b59aa16aca4766bf
diff --git a/vp9/encoder/vp9_encoder.c b/vp9/encoder/vp9_encoder.c
index 047d28d..53c6dd6 100644
--- a/vp9/encoder/vp9_encoder.c
+++ b/vp9/encoder/vp9_encoder.c
@@ -62,8 +62,6 @@
 #define AM_SEGMENT_ID_INACTIVE 7
 #define AM_SEGMENT_ID_ACTIVE 0
 
-#define SHARP_FILTER_QTHRESH 0          /* Q threshold for 8-tap sharp filter */
-
 #define ALTREF_HIGH_PRECISION_MV 1      // Whether to use high precision mv
                                          //  for altref computation.
 #define HIGH_PRECISION_MV_QTHRESH 200   // Q threshold for high precision