ASoC: uniphier: remove redundant check of PLL ID

This patch removes redudant check of PLL ID. struct uniphier_aio_pll
enable member has already been checked at is_valid_pll().

Signed-off-by: Katsuhiro Suzuki <suzuki.katsuhiro@socionext.com>
Signed-off-by: Mark Brown <broonie@kernel.org>