iio: adc: mcp3911: add reset management

Add support for optional HW reset.
If specified, a reset will be asserted during driver probe.

Co-developed-by: Lukas Rauber <lukas.rauber@janitza.de>
Signed-off-by: Lukas Rauber <lukas.rauber@janitza.de>
Signed-off-by: Marcus Folkesson <marcus.folkesson@gmail.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://patch.msgid.link/20250428-mcp3911-fixes-v2-3-406e39330c3d@gmail.com


Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>