ASoC: rt5645: set sel_i2s_pre_div1 to 2

The i2s clock pre-divider 1 is used for both i2s1 and sysclk.
The i2s1 is usually used for the main i2s and the pre-divider
will be set in hw_params function.

However, if i2s2 is used, the pre-divider is not set in the hw_params
function and the default value of i2s clock pre-divider 1 is too high
for sysclk and DMIC usage. Fix by overriding default divider value to 2.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=95681


Tested-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Bard Liao <bardliao@realtek.com>
Signed-off-by: Mark Brown <broonie@kernel.org>