aom/*.h,cosmetics: fix a few typos

Change-Id: I8b739cb0c2395948272893b78b069259bf0a2e31

aom/aom_codec.h

diff --git a/aom/aom_codec.h b/aom/aom_codec.h
index 84454a2..1ecf5f8 100644
--- a/aom/aom_codec.h
+++ b/aom/aom_codec.h
@@ -52,7 +52,7 @@
 // configuration is changed based on the parameter. Note that a aom_codec_err_t
 // is returned, which indicates if the operation was successful or not.
 //
-// Note that for the encoder, the aom_codec_alg_priv_t points to the
+// Note that for the encoder, the aom_codec_alg_priv_t points to
 // the aom_codec_alg_priv structure in av1/av1_cx_iface.c, and for the decoder,
 // the struct in av1/av1_dx_iface.c. Variables such as AV1_COMP cpi are stored
 // here and also used in the core algorithm.

aom/aom_image.h

diff --git a/aom/aom_image.h b/aom/aom_image.h
index 87a2d61..3b71086 100644
--- a/aom/aom_image.h
+++ b/aom/aom_image.h
@@ -169,7 +169,7 @@
  * with the next output aom_image. Its insert_flag is set to either
  * AOM_MIF_ANY_FRAME, or AOM_MIF_ANY_FRAME_LAYER_SPECIFIC if the OBU contains an
  * OBU header extension (i.e. the video contains multiple layers AND the
- * metadata was added using *_LAYER_SPECIFC insert flag if using libaom).
+ * metadata was added using *_LAYER_SPECIFIC insert flag if using libaom).
  */
 typedef enum aom_metadata_insert_flags {
   AOM_MIF_NON_KEY_FRAME = 0, /**< Adds metadata if it's not a keyframe */
@@ -327,7 +327,7 @@
  * example:
  * \code
  * aom_img_wrap(img, fmt, d_w, d_h, stride_align, (unsigned char *)1);
- * ... calculate buffer size and allocate buffer as desribed earlier
+ * ... calculate buffer size and allocate buffer as described earlier
  * aom_img_wrap(img, fmt, d_w, d_h, stride_align, img_data);
  * \endcode
  */

aom/aomcx.h

diff --git a/aom/aomcx.h b/aom/aomcx.h
index 3dfaa64..cae2a79 100644
--- a/aom/aomcx.h
+++ b/aom/aomcx.h
@@ -219,7 +219,7 @@
    */
   AOME_SET_CPUUSED = 13,
 
-  /*!\brief Codec control function to enable automatic set and use alf frames,
+  /*!\brief Codec control function to enable automatic set and use arf frames,
    * unsigned int parameter
    *
    * - 0 = disable