iio:health:max30102: Drop of_match_ptr and use generic fw accessors

This enables use of the driver with ACPI PRP0001 and also removes
an antipattern that I am trying to clear out of IIO to avoid
it being copied into new drivers.

Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Acked-by: Matt Ranostay <matt.ranostay@konsulko.com>
Link: https://lore.kernel.org/r/20200910173242.621168-39-jic23@kernel.org