encoder.c: Fix a comment nit

Suggested by James Zern.

Change-Id: I54adaef5026a0624cc385bbbdec2e92b01328c05

av1/encoder/encoder.c

diff --git a/av1/encoder/encoder.c b/av1/encoder/encoder.c
index 0eaae93..2b93c1e 100644
--- a/av1/encoder/encoder.c
+++ b/av1/encoder/encoder.c
@@ -1530,7 +1530,7 @@
                                           sizeof(*cpi->saliency_map)));
     // Buffer initialization based on MIN_MIB_SIZE_LOG2 to ensure that
     // cpi->sm_scaling_factor buffer is allocated big enough, since we have no
-    // idea of the actual superblock size we gonna use yet.
+    // idea of the actual superblock size we are going to use yet.
     const int min_mi_w_sb = (1 << MIN_MIB_SIZE_LOG2);
     const int min_mi_h_sb = (1 << MIN_MIB_SIZE_LOG2);
     const int max_sb_cols =