vp9_quantizer.c: cleanup -wextra warnings

Change-Id: If5a3c48a8c554018a5d63c1541a2900f15767a00

vp9/encoder/vp9_quantize.c

diff --git a/vp9/encoder/vp9_quantize.c b/vp9/encoder/vp9_quantize.c
index 5206bb6..4d3086d 100644
--- a/vp9/encoder/vp9_quantize.c
+++ b/vp9/encoder/vp9_quantize.c
@@ -32,6 +32,7 @@
                          zbin_ptr[1] + zbin_oq_value };
   const int nzbins[2] = { zbins[0] * -1,
                           zbins[1] * -1 };
+  (void)iscan;
 
   vpx_memset(qcoeff_ptr, 0, count * sizeof(int16_t));
   vpx_memset(dqcoeff_ptr, 0, count * sizeof(int16_t));
@@ -87,6 +88,7 @@
   int idx = 0;
   int idx_arr[1024];
   int i, eob = -1;
+  (void)iscan;
 
   vpx_memset(qcoeff_ptr, 0, n_coeffs * sizeof(int16_t));
   vpx_memset(dqcoeff_ptr, 0, n_coeffs * sizeof(int16_t));