ASoC: rt1015: set snd_soc_dai_ops in rt1015_dai driver

snd_soc_dai_driver should set ops in rt1015_dai driver.
Also make the two variable static to fix sparse warnings.

Fixes: df310074 ("ASoC: rt1015: add rt1015 amplifier driver")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Link: https://lore.kernel.org/r/20200302070522.48104-1-yuehaibing@huawei.com


Signed-off-by: Mark Brown <broonie@kernel.org>