Fix typo: seqence -> sequence

Change-Id: I84d386bd918b391e316ee88f2121bee6de5b14c7
diff --git a/av1/decoder/obu.c b/av1/decoder/obu.c
index fba0e4d..7d59e4d 100644
--- a/av1/decoder/obu.c
+++ b/av1/decoder/obu.c
@@ -176,7 +176,7 @@
   cm->film_grain_params_present = aom_rb_read_bit(rb);
 #endif
 
-  pbi->seqence_header_ready = 1;
+  pbi->sequence_header_ready = 1;
 
   return ((rb->bit_offset - saved_bit_offset + 7) >> 3);
 }