iio: resolver: ad2s1210: add reset gpio support

iio: resolver: ad2s1210: add reset gpio support

This adds support for the optional reset gpio to the ad2s1210 resolver
driver. If the gpio is present in the device tree, it is toggled during
driver probe before the reset of the device initialization. As per the
devicetree bindings, it is expected for the gpio to configured as active
low.

Suggested-by: Michael Hennerich <Michael.Hennerich@analog.com>
Signed-off-by: David Lechner <dlechner@baylibre.com>
Acked-by: Michael Hennerich <michael.hennerich@analog.com>
Link: https://lore.kernel.org/r/20231016154311.38547-1-dlechner@baylibre.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>