iio: magnetometer: yas530: Rename functions and registers

This is a preparation for adding the YAS537 variant.

Functions that are used only by YAS530, YAS532 and YAS533 are renamed from
yas5xx to yas530. Same for the registers.

To avoid part listing in function and registers names, the name of the first
variant is used. Where appropriate, comments were added that these functions
are used by more than one variant.

Functions that will be used by all variants including YAS537 remain in the
naming scheme yas5xx. Or YAS5XX for registers, respectively.
Signed-off-by: Jakob Hauser <jahau@rocketmail.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/344d3b2f5e050eab79ce9962c24781486774d9fb.1660337264.git.jahau@rocketmail.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>