Use aom_reader / aom_writer API to code rest.

The functions aom_encode_pvq_split() and aom_decode_pvq_split() code
 the rest value as raw bits using the od_ec_enc_bits() and
 od_ec_dec_bits() functions.
These code bits in the reverse order as the aom_write_literal() and
 aom_read_literal() functions, so both the encoder and decoder must
 be changed at the same time.
This commit has no impact on metrics but is a bitstream change.

Change-Id: Iee79777f35aebbb23043a7efa7fe439af70348ba

av1/decoder/laplace_decoder.c

@@ -43,11 +43,7 @@ static int aom_decode_pvq_split_(aom_reader *r, od_pvq_codeword_ctx *adapt,
   fctx = 7*ctx + (sum >> shift) - 1;
   msbs = aom_decode_cdf_adapt(r, adapt->pvq_split_cdf[fctx],
    (sum >> shift) + 1, adapt->pvq_split_increment, ACCT_STR);
-#if CONFIG_DAALA_EC
-  if (shift) count = od_ec_dec_bits(&r->ec, shift, ACCT_STR);
-#else
-# error "CONFIG_PVQ currently requires CONFIG_DAALA_EC."
-#endif
+  if (shift) count = aom_read_literal(r, shift, ACCT_STR);
   count += msbs << shift;
   if (count > sum) {
     count = sum;

av1/encoder/laplace_encoder.c

@@ -39,11 +39,7 @@ static void aom_encode_pvq_split(aom_writer *w, od_pvq_codeword_ctx *adapt,
   fctx = 7*ctx + sum - 1;
   aom_encode_cdf_adapt(w, count, adapt->pvq_split_cdf[fctx], sum + 1,
    adapt->pvq_split_increment);
-#if CONFIG_DAALA_EC
-  if (shift) od_ec_enc_bits(&w->ec, rest, shift);
-#else
-# error "CONFIG_PVQ currently requires CONFIG_DAALA_EC."
-#endif
+  if (shift) aom_write_literal(w, rest, shift);
 }
 
 void aom_encode_band_pvq_splits(aom_writer *w, od_pvq_codeword_ctx *adapt,