vpx_fdctNxN_1_c: remove unnecessary store

only output[0] needs to be set, the other values will be ignored in this
case.

Change-Id: I8e9692fc0d6d85700ba46f70c2e899a956023910

vpx_dsp/fwd_txfm.c

@@ -85,7 +85,6 @@ void vpx_fdct4x4_1_c(const int16_t *input, tran_low_t *output, int stride) {
       sum += input[r * stride + c];
 
   output[0] = sum << 1;
-  output[1] = 0;
 }
 
 void vpx_fdct8x8_c(const int16_t *input, tran_low_t *final_output, int stride) {
@@ -182,7 +181,6 @@ void vpx_fdct8x8_1_c(const int16_t *input, tran_low_t *output, int stride) {
       sum += input[r * stride + c];
 
   output[0] = sum;
-  output[1] = 0;
 }
 
 void vpx_fdct16x16_c(const int16_t *input, tran_low_t *output, int stride) {
@@ -373,7 +371,6 @@ void vpx_fdct16x16_1_c(const int16_t *input, tran_low_t *output, int stride) {
       sum += input[r * stride + c];
 
   output[0] = sum >> 1;
-  output[1] = 0;
 }
 
 static INLINE tran_high_t dct_32_round(tran_high_t input) {
@@ -777,7 +774,6 @@ void vpx_fdct32x32_1_c(const int16_t *input, tran_low_t *output, int stride) {
       sum += input[r * stride + c];
 
   output[0] = (tran_low_t)(sum >> 3);
-  output[1] = 0;
 }
 
 #if CONFIG_VP9_HIGHBITDEPTH