ASoC: pcm1681: Fix setting de-emphasis sampling rate selection

The de-emphasis sampling rate selection is controlled by BIT[3:4] of
PCM1681_DEEMPH_CONTROL register. Do proper left shift to set it.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Acked-by: Marek Belisko <marek.belisko@streamunlimited.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org