ASoC: rt5640: Remove the sysclk and sysclk_src checking

Remove the sysclk and sysclk_src checking in the function set_sysclk() to
prevent the PLL power off. It is not getting re-programmed during
subsequent runs after the first run (in BIAS_OFF stage).

Signed-off-by: Oder Chiou <oder_chiou@realtek.com>
Link: https://lore.kernel.org/r/20220210071900.17287-1-oder_chiou@realtek.com
Signed-off-by: Mark Brown <broonie@kernel.org>