crypto: crct10dif_generic - fix duplicated words

Change the doubled word "at" to "at a".

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: linux-crypto@vger.kernel.org
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto/crct10dif_generic.c

@@ -35,7 +35,7 @@ struct chksum_desc_ctx {
 };
 
 /*
- * Steps through buffer one byte at at time, calculates reflected
+ * Steps through buffer one byte at a time, calculates reflected
  * crc using table.
  */