ASoC: rt5640: Set PLL src according to source

rt5640_set_dai_pll set pll source according to given source and
dai id. However, the pll source should be set according to given
source only.

Signed-off-by: Jack Yu <jack.yu@realtek.com>
Signed-off-by: Bard Liao <bardliao@realtek.com>
Signed-off-by: Mark Brown <broonie@kernel.org>