ASoC: rt5645: Separate regmap for rt5645 and rt5650

rt5645.c support both rt5645 and rt5650 codec. And the default
value of registers are not identical. So we use different regmap
for the two codecs.

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