mfd: ti_am335x_tscadc: Use driver data

mfd: ti_am335x_tscadc: Use driver data

So far every sub-cell parameter in this driver was hardcoded: cell name,
cell compatible, specific clock name and desired clock frequency.

As we are about to introduce support for ADC1/magnetic reader, we need a
bit of flexibility. Let's add a driver data structure which will contain
these information.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20211015081506.933180-18-miquel.raynal@bootlin.com