leds: aw200xx: Calculate dts property display_rows in the driver

leds: aw200xx: Calculate dts property display_rows in the driver

Get rid of device tree property "awinic,display-rows". The property
value actually means number of current switches and depends on how LEDs
are connected to the device. It should be calculated manually by max
used LED number. In the same way it is computed automatically now.
Max used LED is taken from LED definition subnodes.

Signed-off-by: George Stark <gnstark@salutedevices.com>
Signed-off-by: Dmitry Rokosov <ddrokosov@salutedevices.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20231125200519.1750-5-ddrokosov@salutedevices.com
Signed-off-by: Lee Jones <lee@kernel.org>